Your sentence is almost perfect! Here's what you wrote:
The peacock's feathers are pretty, but its singing is scratchy.
Let's check it carefully:
- "The peacock's feathers": This means the feathers belong to the peacock, and it is correct with the apostrophe.
- "are pretty": This is a correct description of the feathers.
- "but its singing is scratchy." "Its" is the right word here (not "it's"), meaning belonging to the peacock. "Scratchy" is a good word to describe a rough or not-smooth sound.
So, your sentence is grammatically correct! Good job!