Auto complete is one of the handy features in the Real Studio code editor. Having some context aware help for the syntax is a good thing in every IDE.
In Real Studio you first have this useful feature that Real Studio offers you possible words if you press tab while typing. Like the picture on the right where you see all the classes starting with c.
Same goes on if you type code and Real Studio can show you what methods you can call in that point of code. In this examples you see only methods or properties. The IDE knows that you are not right of an assignment or expression so you can't call functions here. If you want to call a function here, use the call keyword.
And finally on the third picture you can see context help. Real Studio shows you the parameters for this method.
Still autocomplete can be improved. For example if a method if overloaded, you see only one of them and have no way to see other variants. And it's possible (but rare in newer versions) that the IDE fails to offer you completion. Most times because your code before has a compile error.