"Will you want to do the work then?"
Translation:Fyddi di eisiau gwneud y gwaith wedyn?
wedyn has a sense of 'afterwards' - 'will you want to do the work then (after you have done something else)?' I think it might be more common at the end of a sentence, as in the example, than yna, but I'm not sure.
It is closely related to wedi (after).
I have just edited the sentence to make 'afterwards' the main English version rather than 'then'.