When someone studies, they read and learn about something. Studies are also the things people learn about.
Studying is usually good because it means people are trying to learn and understand things.
Examples:
She studies hard for her test.
His studies include math and science.
I like to study animals in the books.
He studies the stars at night.
Her studies of the ancient ruins are very interesting.
The boy studies the big book to learn about the dinosaurs.