A Timestamp, at the most basic level, represents some moment in time.
In cryptocurrency, a timestamp represents the exact moment in time that a block was mined and validated by a blockchain network.
A timestamp can also refer to a moment in time when a transaction was encrypted, confirming the existence of the data compiled in a blockchain transaction.
Cryptocurrency exchanges and wallets also provide transaction timestamps that provide a chronological record of all transactions that have taken place over some period of time in that wallet.
This could include a deposit, a withdrawal, buying or selling an asset, when you first started staking an asset, and more.