What do you understand by the term acceleration? When is it positive and when is it negative?

(N/A) $(i)$ The rate of change of velocity with respect to time is called acceleration.
$(ii)$ Acceleration is considered positive if the velocity of an object increases in the direction of motion.
$(iii)$ Acceleration is considered negative (also known as retardation or deceleration) if the velocity of an object decreases,meaning the acceleration is in the direction opposite to the direction of motion.