What does this symbol on the guitar mean?

I don't know what symbol is in the middle, but the symbol sum appears in pairs, which means that when you sing here, you have to go back and sing the second paragraph, starting from the symbol on the other side, and the "spear" is to slowly sweep the Xuan, and the small horizontal line behind it is the extension of the sign sound, that is, the time after you sweep the Xuan should last for enough beats (time).

And the last TAB should mean line break, which I didn't pay much attention to.