The Buy it Now option on Nifty's on the market allows you (the buyer) to purchase the price set by the seller for their NFT. As a buyer, you can accept and purchase the Buy offers made by other sellers for immediate purchase.
How does the Buy it Now option work?
You can access the Buy options by first heading to the NFT you're looking to purchase and locating the Buy it Now -> Buy option(s) under the Market section:
A screen will pop up showing the Buy Now process. Here, you'll be able to confirm you have a sufficient DAI balance to purchase the NFT. If your DAI balance does not equal the offer made by the seller, you can purchase additional DAI directly from the same screen:
Once the purchase is made, your NFT will be viewable under your Collected tab located on your profile.