"APR" stands for Annual Percentage Rate and is an indicator used primarily in finance to indicate the interest rate charged, on an annual basis, on a loan or investment (not including any fees, commissions, or additional costs).
In other words, the APR indicates the cost of the funds lent, expressed as an annual percentage.
If you decide to invest in a Lending crowdfunding investment offer, you are providing a loan to a company. The APR represents the interest this company will pay you for using your money. In summary:
for the investor: the TAN represents the percentage return you will receive on your invested capital.
For the Issuing Company: the TAN represents the percentage cost it will pay on the financing it receives.