A puddle under the passenger side is often normal air-conditioning condensate: clear water under a parked car on a hot day. The air conditioner removes moisture from cabin air at the evaporator, and that water normally drains under the vehicle.
Water under the car and water in the cabin
Condensate draining under the car is the expected path. Water inside the passenger compartment can instead indicate a blocked or disconnected drain.
What the puddle does not identify by itself
Looking only at water under the car does not identify coolant, washer fluid or fuel. Those are different fluids from normal condensate.
