git fetch downloads the latest from remote without trying to merge or rebase anything.
Then the git reset resets the master branch to what you just fetched. The --hard option changes all the files in your working tree to match the files in origin/master
remote - origin
branch - master
git fetch --all git reset --hard origin/master
If you have any local changes, they will be lost. With or without --hard option, any local commits that haven't been pushed will be lost.[*]
If you have any files that are not tracked by Git (e.g. uploaded user content), these files will not be affected.