Using a EUR/USD one-year futures contract with a forward rate of 1.4100, you can take advantage of the improved interest rate in the USA and guarantee a fixed return. The forward rate is the agreed FX rate used in the contract.
A bank or broker calculates this rate with a mathematical formula that considers different interest rates and the current spot price. The forward rate adds a premium or discount compared to the spot rate depending on market conditions. In preparation for the arbitrage, we enter a futures contract to buy one lot of EUR/USD at a rate of 1.41 in one year.