Step 1 : git checkout <branch_name>
This is obvious to go into that branch.
Step 2 : git pull -s recursive -X theirs
Take remote branch changes and replace with their changes if conflict arise.
Here if you do git status
you will get something like this your branch is ahead of 'origin/master' by 3 commits.
Step 3 : git reset --hard origin/<branch_name>
Step 4 : git fetch
Hard reset your branch.
Enjoy.