In the world of cryptocurrencies, confirmation is a measure of how many blocks have actually passed since a transaction was added to a coin’s blockchain.
The more confirmations that have occurred, the more secure the transaction actually is.
Referring to Bitcoin specifically, six confirmations are advised as a good safe when it comes to larger transactions. Each merchant, as well as the exchange, has to decide how many confirmations they require for each coin.
When it comes to the time between confirmations, it depends on the coin itself, as each coin has a different time frame for how quickly the blocks can be mined. Keep in mind that an unconfirmed transaction is one that is waiting to be added to the blockchain by miners. Each block is then added after that initial block and results in one confirmation. This means that if one confirmation takes 10 minutes, six could take an hour, and so on.