Accounting → Bank Reconciliation (needs the reconcile permission) lists sessions per bank account.
A session
Start Reconciliation takes statement date, opening balance and closing balance, which you type from the statement; nothing checks them against the ledger. Expand a session to see Cleared Balance, Difference, and matched and unmatched payments with Match and Unmatch (silent).
Cleared balance is the opening balance minus the matched payments; Close Reconciliation is enabled only when it equals the closing balance exactly. A closed session cannot be reopened.
Scope
Only bill payments (money out) can be matched. The page says invoice receipts are not reconcilable yet.