Ryan,
Rolls are a rapid succession of notes played on different strings involving the thumb and at least two fingers. The sequence of rolls is usually either thumb/index/middle (ascending or forward) or middle/index/thumb (descending or backward). Just to add to your confusion there are also banjo rolls and chromatic rolls which use a different sequence altogether. But my favorite rolls are definitely cinnamon.
An easy way to start practicing rolls is by fretting minor and major chord patterns on the top three strings and doing the two roll patterns I mentioned. The key is to play the notes smoothly and evenly.
I'll use chords from a commonly used classical chord progression to give you an example:
xxx765 (Dm) - play the descending roll pattern 4 times
xxx786 (Gm) - play the descending roll pattern 4 times
xxx553 (C) - play the descending roll pattern 4 times
xxx565 (F) - play the descending roll pattern 4 times
Try the chord progression with the ascending rolls next. You'll probably have more difficulty doing the ascending rolls.
GL