"Form" does indeed train "practice this week."
"Practice this week" is a qualitative judgment of how a player appears to be playing in practice. Form shows how much a player is capable of performing all of the basketball moves properly. If a player gets out of practice or tired (say, if he plays too few minutes per week, or too many) he will lose the ability to do a double clutch reverse layup properly, for example. So, if a player plays too many minutes in a week, or too few, his form will go down, and he will look worse in practice. If you train form, it forces him to spend those practice hours working his style back into shape, and he will start to look better in practice.
I hope this helps to clarify things. Best of luck with the rest of the season!