What a pull request is
A pull request, or PR, is a request on GitHub: "please merge my branch into yours". It is not a Git command. It is a GitHub feature built around git merge.
The point is the discussion. Before the code joins main, someone else reads it, comments on specific lines, asks questions, and approves. Every software company works this way. Doing it in a college project is good practice and it looks right when someone reviews your GitHub.
The full flow
git switch main
git pull
git switch -c feature/export-csv
# do the work
git add .
git commit -m "Export attendance list to CSV"
git push -u origin feature/export-csv