Hi Jazmin, that means that the primary host would add you to their Service, and you'd be able to see the calendar for bookings and message guests-- you'd be a helping hand to the primary service provider. They could pay you directly, or set up the service through Airbnb to pay you a set percentage.
I would ask the service provider exactly what they'd want you to do. Is it manage their calendar? Communicate? Do the service? Being a service co-host should have the same flexibility that being a homes co-host has.
P.S. If you haven't joined the Virginia Airbnb Host club please do! We have just moved from Facebook to a new Airbnb-built platform-- I'm trying to round up Virginians! (I'm one of the club leaders)
>www.airbnb.com/h/spindlehillfarm
www.airbnb.com/x/wildcrafting
www.airbnb.com/x/incense