a). m/s ... meters per second.
That's a speed.
b). m/s² ... (meters per second) per second.
Acceleration.
c). m²/s ... square meters per second.
Rate of change of area.
Meaningless unit, unless you happen to be
a painter of houses or a mower of lawns.
d). kg-m/s² ... (mass) x (an acceleration).
This is a unit of force.
In fact, it's the definition of "newton".