In this case "drive" is short for "driver current," how much current is being used to direct the voltage in a particular way. For instance, in classic RTL you

In this case "drive" is short for "driver current," how much current is being used to direct the voltage in a particular way. For instance, in classic RTL you have fairly big resistors between power and all your outputs driving them weakly up. But you have NFET transistors that may or may not strongly drive your outputs down. So you've always got a 'H' leading into the outputs but sometimes also a '0'.