Much as you have different accounts under your bank account, you can have more than one account under your Northe account.
"User account" is your account in the Northe app. You may register or log in to your user account from the Northe mobile app.
When you are charging in the Northe app you must select which account to debit for the charging session. These accounts can either be your own personal account "My account" or a shared account "Billing account".
"My account" is the default account under your user account. Unlike a billing account "My account" cannot be shared or debited by other users.
A "Billing account" is created by you or someone else (for example your employer). If you are the administrator of a Billing account you can invite other users. This will allow them to debit the payment method selected for the account. If you are invited to a Billing account, your charging will be debited to the administrator of the account.
If one or more Billing accounts are connected to your user account, you may select between each respective "Billing account" and "My account" in the profile menu (settings).