Are you talking about a hardware wallet like CoolWallet
[1] or software like Bitcoin Wallet
[2]?
Software: I think NFC plays a role here when requesting a payment. For sending, I don't think there is no need for NFC but if you are using one device as cold storage and the another as watch-only, you can use NFC to broadcast transaction just like it works for hardware wallet. See
http://youtube.com/watch?v=kmksAu_ytMg for example.
Hardware wallet: Usually, the transaction is signed inside the wallet and the signed raw transaction is send via NFC to wallet connected to internet to broadcast that transaction. This helps in securing our private key as it never leaves the device and is not exposed to internet.
[1]
https://coolbitx.com/[2]
https://play.google.com/store/apps/details?id=de.schildbach.wallet&hl=en