The acceleration of the body is -5 m / s2. What does it mean?

Acceleration is a vector quantity that shows how the speed of a body changes per unit of time. An acceleration of 5 m / s2 means that the speed of the body has increased by 5 m / s in 1 second.
There was a speed for example 2m / s after 1 second the speed will be 5 m / s more, that is, 2m / s + 5m / s = 7 m / s. After another 1 second, the speed will increase by another 5 m / s, becoming 7m / s + 5m / s = 12m / s.
Acceleration – 5 m / s2 means that the speed of the body in 1 second decreased by 5 m / s.
For example, there was a speed of 12 m / s in 1 second the speed will be 5 m / s less, that is, 12 m / s-5 m / s = 7 m / s. After another 1 second, the speed will decrease by another 5 m / s, becoming 7m / s-5m / s = 2m / s.