In this case let's define right to be the positive direction.

Observe the motion when both the velocity and acceleration are positive.

Observe the motion when both the velocity and acceleration are negative.

Complete this sentence: When the velocity and the acceleration are in the same direction the object ____________________ .

Observe the motion when the velocity is positive and the acceleration is negative.

Observe the motion when the velocity is negative and the acceleration is positive.

In these two situations we generally say that the object is decelerating.

Complete this sentence without using the word "decelerating": When the velocity and the acceleration are in opposite directions the object ____________________ .