Some rhythm styles may be a cross between picking single notes and playing full chords. Some songs may use chords but to make the tune sound right you have to pick specific notes of that chord. This style of playing is a little advanced for this section but I will explain it anyway.
In this 1st example (a section taken from the song Under The Bridge by the Red Hot Chilli Peppers) the tablature is showing what strings are being strummed. Normally in this style of charting rhythm you don't have to pay much attention to the tab numbers. They are only telling you in tab what the chord above is. Depending on how detailed the tab is you may or may not get rhythm instructions, in the case of the example below you have to use the note values attached to tab numbers to help you with the rhythm. Once again showing why it is useful to know how to read sheet music.