At a minimum, the real estate agent manages coordination. Good agents are familiar with the local ordinances and can save you time and hassle (a city I once lived in insisted that homes had to have a city inspector go through prior to listing, and neither I nor my agent knew until we found out from a buyer's agent).

Great agents will organize staging, professional photos (some companies put up "3d" walkthroughs on their websites), open houses, advertising, recommend investing in remodelling to list at higher prices (or when to pass on those things depending on the local market).

Sometimes, paying an agent more than makes up for the cost by getting a better sale price. Other times, it is kinda pointless.

(If you didnt know, seller customarily pays for both agents as well in the US).