A merge conflict occurs when two branches have changes that conflict with each other. This can happen when two people have made changes to the same file(s) on different branches.
For example, if two people have both made changes to the same line of code in the same file, and then try to merge the two branches, a conflict will occur.
To resolve a merge conflict, you must manually review the conflicting changes and decide which changes should be kept and which should be discarded. This can be done by using a version control system such as Git, which will provide a visual interface for comparing the conflicting changes. Once the changes have been reviewed and a decision has been made, the conflicts can be resolved by manually editing the file and committing the changes.