The APR is a measure of how much a given loan will cost you in interest over a calendar year. The figure for the APR takes into account all of the costs associated with the loan, and standardizes the way the rate is expressed. It’s the expression of the interest rate paid on the loan.
When APR figures are quoted on promotional material, they will be accompanied by the term 'typical APR'. This is because stating the APR is a legal requirement, and the rate stated must be that which is offered to at least two thirds of the loan applicants that get approved for that loan, hence making it the ‘typical’ rate offered.
You will see the APR changing if you alter the dial controls because elements such as the price, deposit, and the length of your agreement all have an effect on the APR.