measured in Newtons, [N]. Newtons are abbreviated with a capital "N." Not a lower case. Note too that the force is a capital "F."
m= mass; measured in kilograms [kg]
a = acceleration [m/s2].
In other words, an UNBALANCED force ,F, gives you an acceleration. Whenever you have a change in speed or direction, it is because of an unbalanced for and Newton's 2nd law.