The given function is an IF function where the first argument is a logical test, the second argument is the result if the logical test is true and the third argument is the result if the logical test is false. Depending on whether the result of the logical test is true or false, the respective value will be returned.
IF(logical_test, value_if_true, value_if_false)
In this case, the logical test first compares the value of B3 and D5. As B3 is not greater than D5, the result is false and the value for false will be returned. The value for false result of the logical test is equated by D5-B3 which is equal to 2. Thus the result of the IF function is +2.
