。
When I woke up, I found a bird in my room.
Literal
Eye [subject-が] wake-up-[and-see-てみる][when-と] room [in-に] one-bird [counter-羽] [subject-が] existed.
The counter 羽 (わ) is the dedicated classifier for birds (and, historically, rabbits — a curiosity of old Japanese counting). One bird is 一羽, two birds 二羽, etc. The rest of the sentence is the standard 'wake up and discover something' frame.