Miner Fees are another name for transaction fees that a blockchain network charges to execute and validate transactions on the blockchain network of choice.
Miners are incentivized to do the work of verifying transactions, confirming transactions, and then adding those transactions to a new block, which is then added to the blockchain.
The miners receive their reward in the form of cryptocurrency like Bitcoin (BTC) for completing complex and expensive cryptographic problems faster than the next miner.
Users of the blockchain, which includes individuals, businesses, and even crypto exchanges, pay the transaction fees that the winning miner eventually gets.
See Transaction Fee for more info.