So, that's the key signature, as you know for G major.

所以，这就是 G 大调的调号。

Okay, so that's called a key signature, just like this is called a time signature.

好的，这叫做调号，就像这叫做拍号一样。

I didn't know there was a key signature of a flat on the third line that would take care of all that.

我不知道在第三行有一个降调的音调符号，它可以注明显示这样的问题。