The Ethereum Virtual Machine (EVM) is a virtual machine that executes Ethereum smart contracts. It is a Turing-complete virtual machine which means that it is capable of running any program given enough time and memory. The EVM is responsible for running the Ethereum network, including all the smart contracts that are written on it.
For example, if a user wants to send Ether to another user, they can write a smart contract to do so. This contract is written in a programming language such as Solidity and is then compiled into bytecode, which is then uploaded to the EVM. The EVM then executes the contract and sends the Ether to the other user.