Zaps are bitcoin micropayments. You connect a wallet to your profile, such as Alby or Wallet of Satoshi. This allows you to send and receive zaps.

BTC Sessions has a helpful tutorial on getting started on Nostr that includes setting up an Alby wallet:

https://www.youtube.com/watch?v=qn-Zp491t4Y

If you have more questions, you can ask the #plebchain and #bitcoin communities.