When trading on BeamSwap, as with other AMMs, there are two types of fees to be aware of: gas fees and liquidity provider fees.
Gas Fee
AMMs utilize on-chain logic to process the swapping of tokens between the smart contract in a liquidity pool and the user's wallet. For a successful swap, an amount of gas is required as a fee for processing this transaction.
Some underlying fees are used as gas when interacting with smart contracts on an AMM for the first time: spending approval, and the fee to finally process the transaction over the blockchain. Note that only the first-time approval for a swap between a pair in one direction requires a fee. Subsequent swaps in the same direction do not require approvals, but will only incur the gas fee needed to post the transaction over the blockchain.
Liquidity provider fee
Unlike centralized exchanges, the liquidity on AMMs is made up of pooled funds contributed either by a team or a token community. The incentive to continue to supply funds to the pool is derived from a liquidity fee (currently being 0.3%) off trades being done over a particular pair of assets in a pool. Note that liquidity providers can only benefit from the pool they contribute to and not from any other pool they are not a part of.