Welcome to PF, Gatorgirl.
Just to jump-start it: speed is a scalar measurement, which is defined only by its magnitude; velocity is a vector measurement, which is defined by both magnitude and direction; acceleration is a change of velocity, so it applies if either the magnitude or the direction is altered.
In everyday terms, speed would be something like 100 km/h; velocity would be 100 km/h east; acceleration would be taking a corner or hitting the brakes or gas pedal (brakes would be a negative acceleration, but still an acceleration).