Gas, gasoline, is a kind of fuel. ETH transfer fees are calculated based on gas consumption (ETH miner fee = Gas Limit * Gas Price). Like BTC, ETH transfers also pay for blockchain miners.
ETH transfers are said to consume gas. This value is determined by Gas Price (unit Price) and consumed Gas Limit (quantity). The amount of Gas Limit is generally determined by the ETH smart contract content. Therefore, the higher the Gas Price set by the initiator, the faster the transaction can be packaged. However, ETH can be returned if it has more Gas than it needs.