A Bitcoin ATM is a kiosk that allows a person to exchange Bitcoin and cash. Some Bitcoin ATMs offer bi-directional functionality enabling both the purchase of Bitcoin as well as the sale of Bitcoin for cash. In some cases, Bitcoin ATM providers require users to have an existing account to transact on the machine.
Bitcoin machines are not ATMs in the traditional sense. Bitcoin kiosks are machines which are connected to the Internet, allowing the insertion of cash in exchange for bitcoins given as a paper receipt or by moving money to a public key on the blockchain. They look like traditional ATMs, but Bitcoin kiosks do not connect to a bank account and instead connect the user directly to a Bitcoin exchange.
To help you easily find the places of bitcoin ATMs use this excellent service - Coin ATM Radar. Use them map to find bitcoin or other cryptocurrency ATM locations as well as various alternative crypto-cash exchange services.