The value of the contract for the bank at expiration is given by:

$\text{USD } 50,000,000 \times 1.25 \text{ CAD/USD} = \text{CAD } 62,500,000.$

At expiration, to close out the contract, it will cost the bank:

$\text{USD } 50,000,000 \times 1.13 \text{ CAD/USD} = \text{CAD } 56,500,000.$

Therefore, the final payoff to the bank is:

$\text{CAD } 62,500,000 - \text{CAD } 56,500,000 = \text{CAD } 6,000,000.$

The bank profits because the contracted forward rate (1.25 CAD/USD) is higher than the spot rate at expiration (1.13 CAD/USD). Since the bank is selling USD forward, a weaker USD (lower CAD/USD rate) at expiration means the bank receives more CAD per USD than the market would otherwise provide.