The correct understanding of a message largely depends on a good knowledge of the elements of the language used in that message. A good understanding of Arabic sentences also depends on a good knowledge of Arabic language structure and the words and prepositions that constitute the sentence structure. This is extremely important for a correct understanding to occur. ‘Kâf ’ is one of the Arabic language prepositions. In order to understand the sentence in which Kâf is used, the usage patterns and in what sense kâf is used in the sentence need to be determined. The Kâf is not just a letter that makes up words, but an element that contributes establishing the connection between the elements of the sentence. In terms of this function, there are many types of kâf. Kaf, it is located in Arabic sentences, as a letter, (syllable letter, kafu'l-hıtâb or harf-i car), as a noun, or a pronoun. While it is located in a sentence as ‘harf-i jar’, it is predominantly seen the meaning of similitude (tashbih). And while it is located mostly as similitude (tashbih) in this usage, sometimes it is used as reiteration, causation, superiority, and initiative. If kâf is used as a noun in a sentence, we come across it as the nominative (marfu), accusative (mansub) and genitive (majrur), so form of mubtada, fâil, maf‘ûl, majrur, mudaf and noun of kane. In addition, the usage as a letter of address, and pronoun is other variety of ‘kâf ’. Therefore, we examined the usage of kâf in Arabic sources and its meanings in ayats, which has got a lot of meanings and usages. Finally, we emphasized that prepositions play a very crucial role in understanding and interpreting the sentences.