You pull when you want code from their repo, they pull when they want code from your repo. You don't have permission to push to their repo, so instead you request that they pull from yours.

They already have my branch though! I had to push it to them before I could request they pull it!

No you pushed it to your own GitHub repository. So they need to pull from your repository into theirs.

Though I agree the situation is somewhat muddied by the fact that you can create pull requests for branches in the same repository (even though that's not the normal workflow). GitLab's "merge request" terminology is more accurate for that use case.

Ahh, for me it's pull requests into the central work repo, not GitHub. That is different.

If I loan you money, my money goes to you. If I request a loan from you, your money goes to me.

If I pull your code, your code goes to me. If I request that you pull my code, my code goes to you.