A put-in is where you start your kayak trip — where you put your kayak in the water.
A take-out is just the opposite.
If you're trip is one-way, you need to get back to your car. This is called a shuttle.
For example, if there are 2 kayakers, each would need a car that can transport 2 boats. Both drivers meet at the take-out spot, leave one car and drive with both boats on the other car to the put-in spot. They then paddle back to the first car at the take-out spot, put both boats on the first car and drive back to the put-in to retrieve the second car.