The words "hayvanat bahçesi" form a noun compound. In Turkish, the most common form of noun compound is the '-sI compound' which consists of two nouns, the first of which has no suffix, and the second of which is marked with the "-sI" suffix. Another example in this lesson is "Sultan Ahmet camisi."
whenever a noun has a suffix that ends with vowel (Bahçe + si) the "n" buffer is added before "de" or "dan" nevertheless they didn't begin with a vowel themselves. bankadan = from the bank, bankasından = from his bank. bankalardan = from the banks, bankalarından = from their banks.
why is it hayvanat bahcesi and not hayvanlar bahcesi ? since it's the plural of hayvan
yeah i know I'm Arabic , i just thought there is a grammar rule behind it . thanks a lot :)