"He is going to the office."
Translation:Mae e'n mynd i'r swyddfa.
It keeps introducing these new words at random times! This time it was "o" instead of "e", and in the sentence above it says "ef", when I've only heard of "e"
"o" and "e" are equally correct, it should accept both. One is more used in the north, the other more in the south.
"e" and "ef" are the same thing. In Welsh the final "f" is usually silent. So words like "cyntaf" actually sound like (and are often written) "cynta". The written colloquial language isn't as strict as English and so can reflect spoken dialects.
I'm not really the right person to ask as I probably don't know any more Welsh than you do!
But are you sure it was "ef" or you mean "fe"?
If you look in a dictionary for the translation of the English "he", it will sometimes say: (f)o in North Wales, (f)e in South Wales.
There are rules for when you add the initial F, but I can't remember them. I think it's after conjunctions and some verbs? Also happens in 1st person singular (f)i.