A gas fee is what you pay the network to process a transaction. On Ethereum and most Ethereum layer 2s it's paid in ETH. Robinhood Chain's documentation confirms that it "uses ETH as its native gas token". On layer 2s it is usually a small fraction of mainnet fees, because transactions are processed off the main chain and posted back in batches.
Gas on first-come, first-served chains
On many chains, paying a higher fee gets your transaction processed sooner. On chains with first-come, first-served sequencing, such as Robinhood Chain, extra gas doesn't buy priority, because order is set by arrival time. You still need enough of the gas token in your wallet for every transaction, including approvals and sells.
Practical tip
Keep a small balance of the gas token in your trading wallet at all times. Many traders have been stuck unable to sell a falling token because they spent their last gas on the buy.
Educational content only. Not financial advice.