A (+1.5) point spread indicates that the underdog team will get 1.5 points added to its final score in terms of the point spread for betting purposes.
For example, let's say you see a line that reads Atlanta Hawks (+1.5) vs. Milwaukee Bucks. That bet gives you the option to take the Hawks with 1.5 points added to their final score, or the Bucks with 1.5 points subtracted from their final score.