The Model of Interest Rate Parity states that in the event that two different currencies have different interest rates, then that difference will be reflected in the premium or discount to the price in the future, in order to avoid arbitration without risks.
For example, if interest rates in the U.S. are 3% and the interest rates of Japan are 1%, then the U.S. dollar (USD) should depreciate against the Japanese yen (JPY) by 2% to avoid what is known as risk arbitrage. This price or future exchange rate is expressed in the price at future date (forward) indicated on the current date.