The acceleration of a body refers to the rate at which its velocity changes over time. In this case, if the acceleration of a body is 5 m/s², it means that its velocity is increasing by 5 meters per second every second.
To put it another way, if you were to observe the body's motion, you would notice that its speed (or magnitude of velocity) is increasing by 5 meters per second for every second that passes. This acceleration could be due to various factors, such as the application of a force on the body or the effect of gravity.