Confirmation in Blockchain implies that a transaction has been processed by the network by clearing the consensus process that has been programmed in the system and thus is eligible to be added to the ledger being carried by the corresponding nodes, which are a party to the transaction. Once confirmed, the transactions are considered almost irreversible and tamper evident.

Using Blockcypher or Blockchain.com explorers one can see numbers of confirmations that the transaction has obtained by pasting the transaction ID into the search field of respective explorers. In Bitcoin by design, a transaction will receive atleast 1 confirmation after an average of 10 minutes.