From what I can tell, a special escrow TX is created. This TX has special properties in that once it's created, there are only a few actions that can be taken.
The seller & buyer agree in an encrypted chat on terms to transmit fiat or whatever. The buyer does what is agreed to & posts proof, such as receipt, or seller sees deposit bank.
The seller can finalize escrow & send BCH to buyer if everything went as planned. What seller can't do is send BCH back to self. If dispute arises, then bitcoin.com gets involved
If seller or buyer raises dispute, either can unlock encrypted chat and bitcoin.com can review. Bitcoin.com, as escrow agent, has power to send BCH back to seller or to buyer.
The actual method of transferring fiat or whatever agreed exchange is (could be other things I imagine) is up to the buyer and seller. The categories are only to help search by buyer.
