You did not started on the basics of Robot Framework, but maybe because of the requirements of your task at hand you needed to “jump” to not so usual features of RF.
RemoteLibrary (and its specific implementations) acts like a driver or middleman between a library and the actual RF testing. This was cleverly designed to make possible a RF, programmed in Python, to see libraries keywords created on other languages. For example Java, and in your case from the Swing Java library.
Actually, the first use case, is to have keywords in a library in a different server, where a computer in that network could run the RF tests, but only having the test cases, not a copy of the library. This way, keywords would only needed to be updated on the server.
If you go to robotframework.org and see the standard libraries docs, you find there the RemoteLibrary. There should be valuable information in the User Guide, which I recommend to read at least one time (and review after a major upgrade. This is a note to self ).
The library GitHub project should also have important information. If I am not mistaken, the library SikullyLibrary uses the RemoteLibrary, and has a nice architecture diagram.
I also recommend for you to try the RF demo of SwingLibrary, where you use Jython to test a Java app.