Yeah, scale and potential impact can really influence how important version control is. The stuff I work on can literally (and usually indirectly) affect hundreds of thousands of gamers.
@El'endiaStarman is it correct that a pull request is a request to merge your changes back into the "main" branch of whatever you're developing, that usually needs the approval of someone else?
When you're on a specific branch, you can copy changes from elsewhere into the one you're on (pull) or copy your changes to somewhere else (push).
@NathanMerrill It's slightly different at my work. Individual PRs for each task get merged into master when they're done, then we have a 1.x release branch with possible variants such as 1.80.0 (and .1, .2, etc for hotfixes if needed). We have several environments that are on different releases at any given time.
Probably worth noting that we effectively manage which release our clients have; they don't (directly) interact with our code at all.