No. Not always. It is called tanwīn in Arabic. It is Arabic equivalent of an indefinite article. It is just the consonant 'n' sound connected to the previous letter.
Kitaabu-n : a book Al-kitaabu : the book
Plus it is generally written in Arabic as a diacritical mark
كِتَابٌ - read كِتَابُنْ (not كِتَابُون)
Hope it helps.
jaar-un, a neighbor. when it is written it looks like this جارٌ its usually not written... the short vowels usually arent written either which makes it hard for new learners to pronounce the word without familiarization
And not the most useful or most frequently used words either. I wonder why they took this approach? Maybe because of word simplicity.
The word جارٌ is introduced early in A. S. Tritton's Arabic (Teach Yourself Books; chapter 3, p. 37), perhaps, as you indicate, because it's a simple word, but also the word can refer to a "protected outsider" and so it's an important word historically for the ethical treatment of strangers in an honor-shame culture.