Acceleration is the change in speed divided by the time taken. It is measured in metres per second squared (m/s2). You do not need exact values, but you should be able to judge the size of an everyday acceleration.
A walker or cyclist speeding up gently has an acceleration of about 1 m/s2. For example, a runner who speeds up from 0 to 3 m/s in 3 s has an acceleration of 3 divided by 3, which is 1 m/s2. A car pulling away from traffic lights accelerates at about 2 m/s2.
An object falling freely near the Earth's surface accelerates at about 10 m/s2 because of gravity. A car braking hard in an emergency has a negative acceleration, called a deceleration, of about 8 m/s2.