A VOUT is a transaction outpoint. Each VOUT contains a piece of script which can be used to contain a piece of data, hold a token or lock a quantity of Satoshis. If a VOUT has not been spent, it is referred to as an UTXO and can be used in the creation of a new transaction. Once a VOUT has been used as an input to a Bitcoin Transactions it is considered spent and may be pruned from blockchain records.
Zero value outptuts
VOUTS that do not contain a value in Satoshis are often used to hold scripts that carry large data items or tokens. Predominantly these are used in False Return outputs as a means to attach data to bitcoin transactions These outputs are still valid UTXOs and can be used as inputs in a transaction, with locking conditions being applied as normal. The dust rules implemented early on in Bitcoin's history mean that it will not be possible to create complicated scripts using zero value outputs until miners remove the limits on minimum output values.