Those are a little feature called Reputation Points. If someone especially appreciates or enjoys something you posted, they can leave you positive reputation points (sometimes called karma). They can also leave you a little message. If you click the User CP button, you will see the last 5 people who left you reputation points.
You can leave reputation points for other people by clicking on the little scales on the right hand side of a post, just above the member's Join Date. It brings down a little screen so that you can leave a message with your rep points.
Judging by the number of green squares you have, Guts, lots of people are enjoying your posts!