In Tryton account reconciliation is a process that matches up debits and credit in an Account which balance out to zero.
This allows you to easily see, for example, which payments were for which transactions, and which things still need to be paid for. Any Reconciliation that an Account Move Line is part of is shown by the account move line’s Reconciliation field.
The Reconcile Accounts wizard is used to manually run this account reconciliation.
Some other processes in Tryton will automatically reconcile account move lines when appropriate.