ATM
ATM has 2 meanings
Automated teller machine
An ATM is an automated teller machine. It is a machine that dispenses cash to bank account holders that use a debit card and an PIN (personal identification number).
Example
I'll be there in a bit. I have to stop by the ATM for some cash first.

ATM means automated teller machine
ATM means at the moment. It is an acronym often used for telling someone you're busy and can't type at the keyboard or talk right now.