"Wnei di dynnu llun, plîs?"
Translation:Will you take a picture, please?
llun means 'a picture'. It is also an old word for the Moon which survives in dydd Llun for Monday.
Nowadays, y Lleuad is used for 'the Moon'.
I answered with "Would" instead of "Will". Without wanting to seem pedantic, aren't they both right?
They are different tenses so 'would you' does not work here. Although in English 'would you...?' is perhaps more common in this context, there is not the same sense of brusqueness in using the equivalent of 'will you...?' in Welsh.