Learn Turkish: Binanın dışında bir köpek var. - There is a dog outside the building.

In Turkish, spatial words like dış (outside) act as nouns. To say 'outside the building', Turkish literally says 'at the building's outside'. Dışında is made of dış (outside) + ı (its, possessive ending) + n (a buffer letter) + da (at, locative ending).

Why does bina (building) change to binanın?

Because spatial relationships use possessive grammar. Just like saying 'Ayşe's car', we are saying 'the building's outside'. Bina gets the genitive (possessor) ending -nın to firmly link it to dışında (its outside).

Why is the buffer letter n used in both binanın and dışında?

They are actually used for two different reasons! In binanın, the n prevents two vowels from touching (bina + ın). In dışında, the n is a special buffer used specifically to separate a possessive ending (ı) from a location ending (da).

Why is bir (a/an) in the middle of the sentence instead of at the beginning?