If air resistance is neglected, the object is said to be in free fall. If the height through which the object falls is small compared to the Earth's radius, $g$ can be taken to be constant, equal to $9.8~\textrm{m/s}^2$. Free fall is thus a case of motion with uniform acceleration.
What is meant by: If the height through which the object falls is small compared to the Earth's radius?