Merge Conflict happens when Git can't automatically combine two branches — for example, when two developers edit the same line of the same file in different ways.
To resolve it, open the conflicting file yourself, look at the markers Git shows (<<<<<<<, =======, >>>>>>>), pick or merge the code you need, and save the file. Then let Git know the conflict is resolved with git add and git commit.
You should see
(Merge conflicts are common in collaboration, so knowing how to resolve them matters)