Дар кӯҳсор ҳайвоноти ваҳшӣ: гург, рӯбоҳ, хирс ва бабрҳо мешаванд.
In the mountains are wild animals: wolves, foxes, bears and tigers.
Мо имрӯз ба сайри кӯҳсор меравем.
Today we are going for a walk in the mountains.
Adding the suffix -зор, -сор, -истон to a noun forms a noun for a place. Кӯҳ is mountain, so кӯҳсор is “the place of mountains” which could also be translated as “mountainous region”, “highlands”, or simply “mountains”.
Кӯҳистон is a synonym for кӯҳсор. It would be interesting to find out if they have slightly different meanings or if they are completely interchangeable.