The explanation of kitab, the book, is one of the Prophet`s (s) missions mentioned in many verses of the Holy Quran. Some have viewed the word explanation in these verses to mean interpreting the book and removing the ambiguity from its concepts. In this regard, the concepts of the book are concise and ambiguous, and access to its meaning, except in the light of the interpretation of tradition, is not possible. Some also consider the explanation of the book as another interpretation of the Quranic verses. The paper has been based on the presupposition that one, relying on the semantics of the word in the Divine verses, perceives that explanation is not necessarily for the cases of brevity and, therefore, any attempt for comprehensive and exact communication of Quranic verses and keeping them against any distortion and ambiguity would be known as explanation. But explanation is not limited to communicating words, and includes such things as emphasizing the Qur'anic teachings in various words, describing the words, expressing truths and examples, and giving detailed account of the verses.