finalize early is what is stands for. it means when you pay them the vendor immediatley gets the money. if it's not FE than that would mean you could dispute the deal if they never send you anything or send you some bullshit. it will be up to a moderator to check usually and if they find the vendor for example can't prove he sent a package, then you would get your money back, even though you paid the money to the market like 10 days previous.
this is all hypothetical examples. message me or post comments back here if u have any more questions, I'm glad to help.
in other words. FE= pay immediatley. non FE= disputable, but the vendor gets the money days after the crypto was that actual price, so it can affect vendors when they charge a 200$ for something, but when their money is finnaly released through escrow to them, the value changed and they actually only get $180 for example. sometimes its rises true, but I believe most would rather not gamble with their money, so it's important you realease escrow immediatley after receiving your product.