Im having trouble figuring out list, I have a question regarding the following to lines

private SimpleList<String> merge (SimpleList<String> x, SimpleList<String> y)

private SimpleList<Integer> searchLine(String line, String s)

I just was wondering what is the difference when it says (SimpleList <String>) & then When it just says (String). When SimpleList is not there what can I now do or not do?

2nd Question the after Private SimpleList what is the word in the <> referencing regarding my code?