"He has two hands."
Translation:Er hat zwei Hände.
In standard German, I've only heard zwo when dictating numbers (e.g. telephone numbers), to prevent confusion with drei, or sometimes when counting as in eins, zwo, drei, vier.
But not before a noun as in zwo Hände.
It's possible that some dialects may still keep a gender distinction between zween, zwei, zwo but in the standard I think it's always zwei before a noun. (The originally neuter form.)