Suppose you increase your walking speed from 5m/s to 14m/s in a period of 1 . what is your acceleration?

Acceleration = (change in speed) / (time for the change.

change in speed = (ending speed) - (starting speed)  =  9 m/s.

Acceleration  =  (9 m/s) / (period of 1) .

We don't know the units of the 'period of 1'.
If it means '1 second', then the acceleration is   9 m/s² .

If football was tossed in air without gravity or friction the ball would go into space