Explain the Concept of Miner Extractable Value (MEV) in Simple Terms

Miner Extractable Value (MEV) is the profit that miners (or validators in Proof-of-Stake) can earn by arbitrarily including, excluding, or reordering transactions within the blocks they produce. Since transactions are visible in the public memory pool (mempool) before being confirmed, a miner can see a large pending trade and insert their own profitable transaction right before or after it (e.g. front-running or sandwich attacks).

This ability to manipulate transaction order for profit is MEV.