Defer part of the van's value to the end of the agreement (the balloon, or Guaranteed Future Value) to lower your monthly payments.
When the term ends you can typically: pay the balloon and keep the van, hand it back and walk away (subject to condition/mileage), or part-exchange it into a new agreement. This flexibility is why balloon finance suits businesses that like to refresh their fleet regularly.
Balloon agreements usually cap annual mileage and expect fair wear and tear only — excess mileage or damage charges can apply if you hand the van back. For vans doing high daily mileage, a standard HP agreement is often simpler.