It means, "how much do you have remaining?"
If you're waiting on someone to do something, you may ask them this to get an idea of how much longer it will take for them to complete their work.
In the Southern United States, the word "like" will be used in place of "lack"; see: "How much you like?"
John: I can't come over until I've finished painting my fence.
Mary: How much you lack?
John: I'm nearly done. I have about 30 minutes left.
more than alot, and more than much therefore it becomes "alot-much
I love you alot-much