The spelling of the word "Reyba" can be explained through the use of the International Phonetic Alphabet (IPA). In IPA, "R" represents the voiced alveolar trill, "ey" represents the diphthong /eɪ/, and "b" represents the voiced bilabial stop. The stress falls on the first syllable "Rey," which is pronounced /reɪ/. The second syllable "ba" is pronounced /bə/. Altogether, the word "Reyba" is pronounced /ˈreɪ.bə/, with the emphasis on the first syllable.