Suggestion: The sentence in the original posting might be interpreted as follows:
There is a 50VA transformer. As a piece of the hardware it is 50VA and it is assumed that it cannot be bigger, modifed or changed. Then, the transformer has primary winding taps at 120V and 240V. Consequently, if it is supplied by 220V it will have VA220=(220V/240V)x50VA=45.8333....VA
Alternately, there might be something similar to the transformer load.