dzien dobry 'al' in arabic is like 'the' in english. Now, book (noun) in arabic is 'kitab'. But when grammar is concerned, that is when we use the noun in a sentence, we need to specify the sound of the last letter in the word. For kitab, we can use 'kitabun', 'kitaban' or 'kitaben'. For example, in the sentence: I found a book on the table, you use 'kitaban'. Or if you say: This is an interesting book, you use kitabun. In arabic this is called 'tanween', that is adding the sound 'n' at the end of the noun. But I think this is an advanced topic if you are a beginner. for verbs: you can say: I wrote, then the wrote is like 'katabtu' 'Katibun' (writer) is noun duwetzania