Harmonica tabs look something like this:
5 -4 3 -2 1
The numbers tell you what hole you are supposed to play, and a minus sign before a number means a draw note. So, a "5" would mean a 5 blow.. and a "-4" would mean a 4 draw. It's that simple! After you know how to play a song, don't even think about the numbers.
Looking for tablature go here:
NOTE: It is not possible to figure out the rhythm of a song from harmonica tabs. Tabs just tell you what holes to play. They don't tell you how long you are supposed to hold those notes, or how much you should pause between them, etc. So, unless you already know the song, it's not easy to figure it out from tablature alone.
Sheet music on the other hand, does tell about the rhythm of a song. However, learning to read sheet music can be difficult and time consuming. Tabs are only good if you are already familiar with the tune.