/ɡʊ mˈbʲanːiː ˈdʲiə/
Let's break it down:
* ɡʊ: A voiced velar stop /g/ followed by a short rounded back vowel /ʊ/ (like the "oo" in "foot"). The "G" is often lenited (softened) in Irish, which affects its pronunciation slightly.
* mˈbʲanːiː: This represents the lenited "mbeannaí".
* m: A bilabial nasal consonant /m/.
* ˈbʲanːiː: This is the stressed syllable. The palatalisation ('ʲ') is crucial and affects the 'b' sound, making it a palatalized voiced bilabial stop. The 'n' is also often palatalized. The vowel /iː/ is a long high front unrounded vowel (like the "ee" in "see"). The 'ː' indicates length.
* ˈdʲiə: This is the final word, "Dia" (God).
* ˈdʲiə: The 'd' is palatalized here, too, represented by the 'ʲ' symbol, influencing its sound. The vowel /iə/ is a diphthong, a sound that glides from /i/ to /ə/ (a schwa, a neutral vowel sound).
Important Note: The palatalization (the 'ʲ') is extremely important for accurate pronunciation and is what makes the 'b' and 'd' sounds softer and less harsh than the English 'b' and 'd'. Without palatalization, the pronunciation will sound significantly different and less natural to a native speaker. Listening to a native speaker is the best way to master this. You can find audio recordings online.