The code will log `10` to the console. In the function call `multiply(5)`, only one argument is provided, which is assigned to the parameter `a`. Since no value is provided for the parameter `b`, its default value of 2 is used. The function then calculates 5 * 2, resulting in 10. This is a simple example of how default parameters can make functions more flexible. Without default parameters, this function would either need additional logic to handle the missing second argument or would return `NaN` (since multiplying a number by `undefined` results in `NaN`). Default parameters allow you to write more concise code by eliminating boilerplate parameter checking while still providing full flexibility for callers to override the defaults when needed.