I imagine this is the famous “carried interest”
It is payment for a service or product that has not been delivered yet. A good example is if you pay me per storm ahead of time to snow plow your parking lot. The income geets deferred until it snows, then when I plow that part of the payment becomes income that year.
An even simpler example is when you buy a gift card...the retailer defers the income until the gift card is used.
I remember years ago Best Buy tried to claim a huge increase in revenue to boost the stock price, but the analysts were all over it fast because so much of the revenue was gift cards; in fact the analysts at the time claimed that as much as 15% of the revenue from the gift cards would never be claimed as income because so many gift cards died in a drawer and were never used.