What is it called when a treble and bass staffs together

This is called the Grand Staff. If you are learning to play an instrument, you really need to find these things out on your own.

I am curious as to why you are asking these types of questions. Are you studying a band or orchestra instrument, or maybe even piano? Or, is this something for a music class in school? I have been a music and private teacher of instruments, especially piano, for a long time.

I am trying to learn piano on my own. Piano for dummies was a good book for me. It explained grand staffing and other basic questions. What ever instrument you want to play has one. Plain simple, and basic. Then you can go to other books, scales and cords in more detail. I think the fun of learning to play an instrument is teaching yourself. I may get slammed by the teachers but I am having fun learning on my own. I feel it is more of an accomplishment.
Practice, practice, practice and then practice again. The more you use your instrument the more familiar and easier it becomes.
Your question was a valid one.