The spelling of the word "re warns" can be confusing as it contains two syllables with silent letters. The first syllable "re" is pronounced as /riː/ and means "again" or "back". The second syllable "warns" is pronounced as /wɔːnz/ and means "gives a warning". The silent "e" at the end of the word is there to indicate that the vowel "a" should be pronounced as a long vowel sound. Therefore, the correct pronunciation of "re warns" is /riː wɔːnz/.