This is the transaction fee. When performing a transaction such as transferring an Ether to another address, the GAS is required to perform this operation.
Transaction fees, which can increase sharply depending on the use of blockchain, are a deterrent to mass use. Blockchain developers are always looking for ways to limit costs for users.
With GSN, the Ethereum Gas Station Network, it is possible for DApp users to interact with Ethereum contracts without needing ETH for transaction fees.
