Hi! The advice of Carlos to his cousin means that whenever you are planning a traveling, before getting on a plane, bus or train you must have to stay in a room specifically indicated for the passengers to wait until the time of boarding, this is the correct way to have a successful trip with no problems.
las frutas means "the fruit" and your incomplete sentence describes that you are making "juice" and it is common sense that juice is made out of fruit, not a fork or "the cold".
