Hello! It all depends on exactly what you wish to create and the source of your media.
What sort of content/movies do you wish to produce? How are you looking to stream live, or offer recorded / video on demand? In any event, if your media is something that can be recorded or broadcast either primarily from either a camera (webcam, phone, stand-alone video camera etc...), devices of their own accord (modern game consoles, phones) or captured from your PC (games or other programs), you may not need video capture hardware at all. Instead, you may be able to use screen capture/recording/broadcast software and/or video editing if necessary. There are many of them with some of the best even being free/libre and open source! I'll get to them in a moment
Now, if you're going to be capturing media from various or more difficult sources (such as older generation/retro hardware that will need adapters, or grabbing from different sorts of antenna/cable/satellite TV directly, etc) , want/need to offload some of the encoding work to a discrete device, or are looking to have a way more intricate setup/home studio, there is video capture hardware available. I'm not extremely well versed in this arena, but outside of professional grade (and extremely expensive) gear and a host outdated consumer capture cards that haven't changed much in the past two decades or so, there are some newer devices targeting the streamer and online content creator market. For instance, Elgato ( https://www.elgato.com/en ) is known to be of decent quality and was recently acquired by PC component manufacturer Corsair, with their 4K60 Pro Mk2 (internal, PCI-E) or 4K60 S+ (external) as their newest capture devices. Another company with a good reputation is AVerMedia ( https://www.avermedia.com/us/), with their LiveGamer 4K (internal), and LiveGamer Ultra (External, only records at 4K30) and LiveGamer BOLT (External, 4K60 but requires Thunderbolt 3 connectivity). Both companies also have an assortment of other products that are more affordable if you only need 1080P broadcast support - just be sure to get the latest revisions/updates. There are also a bunch of "no name" capture cards you can find out there on Amazon , but that can be a gamble.
Most of the aforementioned capture cards also come with either their own proprietary or some sort of partnered software, yet much of the time that's not the best solution available. Instead, I'd look to the following software which can be used regardless if it is captured from software or hardware.
For capture/streaming: OBS Studio ( https://obsproject.com/ ) - Easily one of the most popular and powerful media capture , recording, and streaming suites around, OBS Studio is even free (as in nothing to pay, and as in the concept of freedom) and open source! OBS Studio can be used to to capture video from multiple sources, from hardware like webcams , microphones, and capture cards, to software sources like media, games, or other things running on your PC; including custom graphics/overlays/effects and the like. It has support/protocols for all the major livestreaming and video hosting sites like Twitch or YouTube, along with newer protocols like PeerTube. Depending on what you want to do, such as streaming as you game, OBS Studio may be all you need! Thanks to its open source nature, OBS Studio is often customized by certain sites or hardware manufacturers , such as the "Streamlabs OBS" version. There are some alternatives to OBS out there as well, from lots of smaller no-name programs to the proprietary "XSplit", noting them for the sake of completeness. However, OBS Studio is favored by many and there are a great deal of tutorials and instructional videos out there on its use.
If you're not going to be only livestreaming, you may have interest in video production/editing software. There is a wide array of different kinds available and I'm not incredibly well versed in the usage thereof, but I'll give a bit of an overview of a few of the better options. Much in the same way that people gravitate toward Adobe Photoshop for image editing despite its cost (mitigated more often then not by piracy in many cases) and complexity, some prefer similar professional video editors like Adobe Premiere Pro or Sony Vegas. One you may be less familiar with is DaVinci Resolve (Studio) ( https://www.blackmagicdesign.com/products/davinciresolve/ ). Amazingly, it has a free version in addition to its paid "Studio" variant ( $300, which is quite inexpensive for its kind of software) and even natively supports Linux! These kinds of programs are usually complete overkill for most content creators not working at a professional level, but I mention them for completeness' sake. There are a wide variety of other video editors ranging from the very simple (such as the "Video Editor" default Windows 10 app, the successor to the Windows MovieMaker of yesteryear) to those nearly as power and complex as the highest professional tier. To narrow it down a bit I'll be listing free/libre open source video editors that run on Windows as well as other OSes and are updated with relative frequency.
Kdenlive, Openshot, and Shotcut all have moderate to advanced levels of features, while Avidemux is most suited for simple / basic editing. There are varied tutorials online for the use of these editors and for general video editing concepts as well.
So that should hopefully get your started. Ultimately, its about what kind of content creation and streaming needs you have. Thankfully these days the barrier to entry is rather low from a technological or cost viewpoint, so with luck you'll be making content soon.