I am currently studying and trying to learn Ulster Irish and I have come across the phrase "fá dtaobh de" often pronounced as "fadúda", and I'm not sure what it means.

I am aware that faoi is often pronounced as fá in Ulster Irish, however I have read that fá dtaobh de is used in the exact same context as faoi, this leads me to ask if there is ever a context in Ulster where just fá is used? Also I would like to ask if there is any other more specific translation for fá dtaobh de?

It means the same as "i dtaobh" (regarding, about, concerning).