The attempted merge has copied files from both branches and attempt to merge. Obviously, there are conflicts and these have been flagged. These changes have not been saved to the repository, simply merged in your working directory.
These newly generated files contains the list of conflicts and possible merged file. You can iterate through the list of conflicts using applications like Tortoise Merge which comes with Tortoise SVN.
You can try the revert command on the branch/trunk to revert back to the specific revision. Or you can checkout the branch/trunk again.