it just means that you hot route them to block (most likely always going to refer to a HB) and usually done on various play action plays( play action is no bueno)
anyway you do this by hot routing in the standard fashion (if you need help with that lemmo know but its very basic so im assuming you know how to hot rte) the running backs Icon Ex: triange or L1(ps3) and then R1 to blk right and L1 to block left.
for example you wanna hout rte you wr on the right to a cur you go thru the motions to get to your hot rtes and you press down to put him on a curl , well its just that simple to blk him as well. instead of pressing down to curl pres r1/l1 to block him. those buttons will always correspond to blocking hot rtes.