When you see 'Changes must be committed or stashed,' Git is indicating that local changes need handling before it can pull from the remote branch. This is because Git prioritizes a clean working directory for seamless merging. To proceed, either commit your changes with `git commit -m 'your message'`, or stash them using `git stash`, which saves changes temporarily without a commit. After stashing, you can pull updates with `git pull` and later reapply your stashed changes using `git stash apply`. This process maintains local and remote coherence, preventing merge conflicts and ensuring the repository's history is intact.