I coach in CA. Need more info but basically most offensive systems have a numbering system that tells which "hole" the play is going to. I name the right side with even numbers from the middle to the outside from 2-4-6-8. Odd numbers to the left 1-3-5-7. I name our running back the 30 back and the full back the 20 back. So if I call "36 BLAST". The 3 indicates the 30 back is getting the ball to the 6 hole, BLAST is the type of blocking. Lead or double team, whatever.
The better teams will have blocking rules- TKO,GOD, Etc. If not general rule would be put your head between the defender you are blocking and the hole that is called. Example to follow up on Rick's post. If you are the right tackle on a 36 blast, you would block the defensive tackle with your left shoulder and your head between the defender and the 6 hole.