what is meant by background removal on Facebook cover gig?

[abi_graphics]

I'm new on Fiverr and wants to publish a gig for designing Facebook cover. For that reason I visited a few giga in order to know how to create a gig. But here I found a sentence which confusing i e "Desktop & Mobile cover +source file Facebook cover optimized for desktop & mobile+ Background remove+ source file". I want to know that what is meant by background removal in this kind gig.

[alifshah01]

1 hour ago, abi_graphics said:

background removal

They can offer different services and extra offers to attract buyer. You can earn more if you add extra service. It's just a way to earn more.  You don't need to worry about it.