My friend told me about a tens unit she uses for her back pain. What is a tens unit, and will it work for me?

May help! Especially if you have pain and spasm. Tens units can have multiple electro conducting pads that you apply to the painful area. Can send electric impulses through the skin to deeper structures like the muscles to make them contract and relax. Also by stimulating nerve endings you can release endorphins that are the bodies own pain relieving substances and at the same time can relieve spasms.
TENS. Tens stands for "transcutaneous electrical nerve stimulation". There are no significant studies to back up its regular use. However its use on individual basis can be determined and considered.