When conflicts happen while merging, git will add for you something like that in each problematic file :
[code language="bash"]
<<<<<<< HEAD
text that is in the HEAD branch
=======
text that is in the dev branch
>>>>>>> dev
[/code]
To resolve the conflicts, simply remove the text that you don't want as well as the tags git added to help you.
Finally confirm the merge with :
[code language="bash"]
git commit -am "Resolved conflicts while merging"
git push -u origin master
[/code]