This is simply an old way of saying “does”. Long ago, English put -th on the end of a verb for he, she, or it: he doth, she hath, it raineth. Today we say does, has, rains. You will see “doth” in Shakespeare, in old church English, and when someone copies that high old style for a joke or a solemn feeling. It is not a different verb and it does not add a new meaning; it is “does” in old clothes. Nobody uses it in normal speech unless they are being funny or theatrical. A line many people still quote is about someone who says “no” so hard that you start to doubt them: “The lady doth protest too much.” If you write “doth” in a school essay about today, it will sound like a costume.