When playing a cord, G for example is strumed you hit the low bass note then strum then the 3rd string from the top then strum the cord again and keep that up til you can keep a good rythm with what you are playing. It is a technique for rythm guitar to kind of spice up there cords a little. I hope I have answered your question and if I have not then maybe someone with a little more inteligence will better answer your question.