SAM and SMV are units of measuring standard minutes of a task or an operation of a garment.
SAM stands for Standard Allowed Minutes and
SMV stands for Standard Minute Value.
When someone says sewing SAM of garment is 15 minutes, it means that particular garment should take 15 minute to complete sewing task by a standard worker.
Garment SAM is summation of SAM of number of operations those are performed to make the garment.
See Also: How to Calculate SAM of a Garment?