0.25% of this trade fee goes to the Liquidity Providers who provide liquidity for that pool. It is added to the pool balance.
If previously there were 100 SLP tokens representing 100 ETH and 100 SRM each token would be worth 1 ETH & 1 SRM.
If one user trade 10 ETH for 10 SRM, and another traded 10 SRM for 10 ETH, then there would now be 100.025 ETH and 100.025 SRM.
This means each LP token would be worth 1.00025 ETH and 1.00025 SRM now when it is withdrawn.