I saw sloth in the movie
My piano is pricey.
The aroma has good scent.
I like to go out and run ,eat and play instrument.

I saw sloths in the movie.
>> When talking about general countable nouns, use plural forms of nouns.

My piano is pricey.
CORRECT!

The aroma has good scent.
CORRECT!

I like to go out and run ,eat and play instrument.
CORRECT!

Hello, Lily! Please be careful with the singular, plural noun rules.