When you are near the end of your lease term, if you lease another Chrysler, the company will let you out of your last specified number of payments. Basically the money from your previous lease goes into your new lease.
It basically means that they will let you out of your last few payments if you decide to lease another Chrysler. It is a good deal if you take advantage of it. If you don't it is still ok because you will save money on not paying for another vehicle.
A pull-ahead program is for existing lease customers near the end of their lease terms. The offer is for Chrysler to excuse a number of monthly payments on the old lease, in exchange for you committing to a new lease on a new car. Any existing balance can be rolled into your new contract with $0 out-of-pocket.