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?"
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.
Mary: How much you lack?
John: I'm nearly done. I have about 30 minutes left.
by vmadman June 17, 2022
Get the How much you lack?mug. Come on, why did you look this up? Come and be a, why did you look this up? Oliver, Josh, Jack and Ben. LoL Yolo. 🤗💩🦄😇😱🖕
by William Shakes The Speare May 25, 2016
Get the Why did you look this up?mug. 
prob lee know’s most iconic quote ever. he said it many times, even in TATH. lee know, you know (i know, lee know) the kpop idol… no? NO? BRUH GO LOOK STRAY KIDS UP RN THEY’RE AWESOME
by StrawberryKat April 27, 2023
Get the you know, i know, lee knowmug. by awdhjaowfh December 31, 2023
Get the You lost.mug. by Bigmeat07 February 14, 2022
Get the I love you moremug. by PCPL May 29, 2023
Get the YOU NAH WAH GOAL!mug.