From Coinbureau:
Vyper is a smart contract language paradigm deriving from Python 3 syntax and conventions and targeting the Ethereum Virtual Machine (EVM).
The EVM is a simulated global singleton computer which runs parallel to the block-chained ledger on Ethereum, allowing for the construction of more complex transactions and conditional self-executing agreements encoded smart contract objects.
The Ethereum platform itself is featureless and value agnostic, providing only the backbone of how smart contracts are to be put together and in the context of what applications.
Vyper is intended to be leveraged with the upcoming transition to Proof-of-Stake (Casper) and provide a more pragmatic minimalist regime for reading and writing of smart contracts, with focus on auditability, syntactical simplicity and straightforwardness.