A pull request is a request for people to review proposed changes and decide whether to combine them with a shared project. It is like showing a draft to your team before adding it to the main notebook.
The request usually shows which files changed and lets teammates discuss the work. Automated checks may also run to look for problems before the changes are merged.
Despite its name, opening a pull request does not automatically pull code onto your computer. It is a collaboration and review step on a code hosting service.