0x4a25d94a?0x4a25d94a is the function selector for swapTokensForExactETH(uint256,uint256,address[],address,uint256). Swaps tokens to receive an exact amount of ETH.
When a transaction's data begins with 0x4a25d94a, it is calling swapTokensForExactETH. The selector is the first four bytes of the keccak-256 hash of the signature swapTokensForExactETH(uint256,uint256,address[],address,uint256), which is how wallets and explorers work out which function a payload is for.