Convert VAh to kWh

You need to know the power factor, which is highly depedant on your application. Then you simply use this formula: $$ P = S * PF $$ where

P = actual energy
S = apparent energy
PF= Power Factor

This answer tells us, that power factor in general public households can be expected to be greater than 0.9.

You can’t convert them.

All you know is that the actual power(’s absolute value) is ≤ the apparent power. The actual power might be 0 (purely inductive or capacitive load) or negative (if you are analyzing a generator). It might also be = the apparent power (purely resistive load).

As for the units, VA and W are equivalent.

As for the energy, give than the power is the derivative of the energy, you have the same result that actual energy(’s absolute value) is ≤ the apparent energy, and that VAh and Wh are equivalent units.