What Is the ‘Nonce’ and Its Role in the PoW Component of the PoA Template?

The 'nonce' is a randomly chosen or iterated number that a miner includes in the block header. The miner's goal is to find a nonce that, when hashed together with the rest of the block data, produces a resulting hash value that is below the network's current difficulty target.

This trial-and-error process is the 'work' in Proof-of-Work, and the valid nonce is proof that the work was performed.