What is the bass and treble staffs connected by a brace and a bar line in music?

Answer 1

The grand staff consists of a treble stave and a bass stave. They are connected by a vertical line creating a "system". The presence of this vertical line signifies that the two staves (treble and bass) are to be played at the same time.

Answer 2

I'm not sure what you mean by connect, however, the treble and bass staffs can be combined into something called the Grand Staff, by connecting them with a straight vertical line at the far left of the staves and a squiggly bracket, just to its left.

In another way the treble and bass staffs are connected through the note middle C. The lowest line on the treble clef is the note "E", and "D" is that note in a space just under the staff. In the same way the top line in the bass staff is the note "A" and "B" is the note in that top space above the staff. In between these two staves is the note "C" which is either one ledger line below the staff in the treble clef or one ledger line above in the bass staff. This one note with two spellings (depending on the clef) is really what connects these two staves.