You can double click on the conflicted item in your changes list. Now the modeler provides more information about it and shows you a before and after compare. I hope that helps.
Hi Du,
A conflict would show in the changes tab in the modeler. You can right click them and choose how to resolve them. Here is a good blog that describes how to do this.
https://www.mendix.com/blog/resolving-commit-conflicts/
If you have a conflict outside of the modeler (for example a sass file). You can use SVN 1.7 to resolve it (make sure to use this specific version).
Hope this helps!