Conflicts arise when two commits were made that both influenced the same document. There's a good blog post on conflict resolution here that might help you learn how to resolve conflicts:

Resolving Commit Conflicts by Adam Fothergill

If you don't see any conflicts in your “changes” tab, you'll have to resolve a conflict in your project folder using TortoiseSVN for instance, but that's a different method than the one mentioned in the blog post.