A scalar is specified by magnitude and units only. For example, my car has 375 hp, a "D" cell battery is 1.5 volts or the cost of that article is $10.00.
In addition to magnitude and units, a vector must be specified with direction and point of application. For example, the force vector acting on the desk has a magnitude of 25 lbs, a direction down and to the right (45 degrees with the horizon), and contacts the left corner of the desk.
A force vector is usually drawn to some convenient scale. We might draw the above 25 lb. force vector 1-1/4 inches long (each 1/4" would then represent 5 lbs of force).
If you wanted to add a force vector of 10 lbs acting downward on the opposite corner of the desk, you would show it as 1/2" long.