Snakes don’t have ears, they can hear you coming though.
They “hear” by being close to the ground, and feeling vibrations move up through their bones.
Other than that, their main method of gleaning information from the world around them is by smelling with their tongues.
The tongue darts out, picks up chemicals and other environmental indicators, and then brings them back into the snake’s mouth, where they’re deposited on an organ in the roof of the mouth.
This organ, called the Jacobson’s organ, can detect even the tiniest of changes in the air, helping the snake to sense danger and locate supper.