Question

if an object is falling on earth at a terminal velocity of 140 km/hr, does that mean that the acceleration is ZERO?

Answer 1

If he's falling in a straight line and his speed is not changing, that tells you that his acceleration is zero.

And THAT tells you that the forces on him are balanced, the net force acting on him is zero, and his motion is the same as it would be if there were NO force acting on him.