Counter offers are an available method to allow some back and forth between a seller and a potential buyer.
When you receive an offer for one of your NFTs that doesn't satisfy you, you can then send a counter offer to the user with an amount you would be willing to accept.
The user will receive a notification and then has the option to modify or cancel their offer.
If they choose to modify the offer to match your counter offer, you will still need to accept the new offer.
NOTE: You can't counteroffer a Collection Offer