In formal Guitar TAB, you may also notice a curved line over the top of the slide, this is a reminder that you only pick the first note of the slide. If there isn't a curved line, it means to pick both notes.
What does a curved line on a guitar tab mean?
The curved line represents hammer-ons, pull-offs, or both. The above tab is telling you to play the 7th fret of the A-string and then hammer-on to the 8th fret. It is then telling you to play the 8th fret of the A-string, and then pull-off to the 7th fret.
What does a bend look like on tab?
In guitar tablature, a bend is indicated by a curved arrow and either a number or a fraction (or both) at the peak of the arrow, which tells you how many whole steps to bend the note.