Bankgirot is a proprietary clearing system (a giro) in Sweden used for transactions such as bill payments. It is owned by multiple Swedish banking conglomerates. The clearing system is connected with the banks enabling payments to be received directly into bank accounts. Swedish Bankgiro numbers are in principle only short versions of bank account numbers. They have seven or eight digits. Bankgiro numbers can't be used when paying from other countries or in other currencies than SEK. Instead the IBAN number of the actual bank account should be used for that. History.
https://en.wikipedia.org/wiki/Bankgirot