What is "layover"?
A "layover" is a stop between flights, also called a connection. While direct flights go straight to your destination, when your flight stops somewhere else before your final destination, it's called a "layover". In this case, he is asking how long they have to wait on their stop before they go on to their final destination. Ex: As long as the layover is less than 2 hours I don't mind. Ex: The ticket is cheaper with a layover.