The phrase "be one case" is spelled using the International Phonetic Alphabet as /bi wʌn keɪs/. The first sound, /b/, is a voiced bilabial stop. The following /i/ represents a high front vowel. The next syllable, /wʌn/, is made up of the consonant sound /w/ and the vowel sound /ʌ/ which is a mid-central vowel. Finally, /keɪs/ is spelled with the voiceless velar stop /k/, the diphthong /eɪ/ and the voiced alveolar fricative /s/.
There is no recognized dictionary definition for the phrase "be one case".