Questions about Ethereum are off topic. A blockchain-based "smart contract" system with a Turing-complete contract programming language. Questions about Ethereum should be asked on the dedicated Ethereum site: https://ethereum.stackexchange.com.
Ethereum is a "Bitcoin 2.0 / Web 3.0" distributed computing system.
Like Bitcoin, Ethereum uses a blockchain to store data and a virtual machine running a stack-based scripting language to act on transactions. Ethereum takes this further than Bitcoin by having a Turing-complete scripting language, with computing time allocated using a pay-per-instruction scheme.
Contracts on the blockchain are accessed using an HTML/JavaScript interface, this combination is known as a "Dapp", a Distributed Application. Dapps can query contract state locally and send transactions to the network. The results of contract code running in response to those transactions will be incorporated into the blockchain by a consensus network of Bitcoin-style miners.
The entire Ethereum network has the processing power of a 1999-era mobile phone, and given the costs of computing and storage on the network it should not be used for computationally or storage heavy tasks. Rather it should be used to publish and validate important state information.
For more information see - https://ethereum.org/
