A curved line and the letter H indicates a hammer-on. The first note is played but the second note is produced by hammering on the left hand finger, which plays the second note.
A curved line and the letter P indicates a pull-off. The first note is played but the second note is produced by pulling off the left hand finger to sound the second note.
The letter S and a straight line indicates a slide. If the line comes from below the number, slide from a lower fret but if the line is above the number, slide from a higher fret. The bracketed number in the tab is the fret to slide from.
The letter B and a curved line represents a bend. The note is played by the left hand finger which bends the string (from the note indicated in the tab to the pitch of the note in brackets).
Harmonics are a bell like sound produced by touching the string lightly above the fretwire with a left hand finger. The string is not pressed against the fretboard. Harmonics are indicated with a dot and the abbreviation har. below the tab numbers.