In transactions, banking, I have two figure - one with the bank balance, then underneath an "in quickbooks" figure which is minus but I don't know why?

The Bank is your actual bank balance.

The quickbooks figure is your "bank account" in quickbooks. 

This is used to reconcile the quickbooks records with the actual bank account records.

Go to the accounts > bank account > account history and you'll see the actual entries in the quickbooks account. Any missing entries will have to be added, either payment to suppliers, where you have a bill to pay, or money in from customers, where you have received money for an invoice. 

Hopefully that helps?

I can provide more details but that should point you in the right direction.

Rosco