Gas fees or minting fees are a transaction fee on the Ethereum blockchain. When you make transactions, such as purchasing an NFT, you will need enough ETH in your wallet for the initial purchase and the associated gas fees. The gas fee enables your transaction to be logged on the Ethereum network.
The price of gas is volatile and fluctuates based on the supply of miners who receive the gas for the transaction vs the demand from consumers making transactions. A user enters the gas price they want to pay, a suggested fee is always shown by the wallet you are using (eg Metamask) to make the transaction. If the cost of gas price exceeds the fee you offered to pay your transaction could fail and the gas fee will be lost without the transaction confirming.
Gas fees are taken by the Ethereum. Lost gas fees are non-refundable. Move forward at your own risk.