The spelling of the word "GRONNA" can be explained using the International Phonetic Alphabet (IPA). The first sound is /ɡ/, which represents the "g" sound as in "goat." The next sound is /r/, which represents the "r" sound as in "red." The third sound is /ɒ/, which represents the "o" sound in British English as in "hot." The final sound is /nə/, which represents the unstressed schwa sound, which is similar to the "uh" sound as in "sofa." Therefore, the spelling of "GRONNA" accurately represents these four sounds, as indicated by the IPA phonetic transcription.