Theory:

     After much discussion, Owlie’s cage was shifted to the library. It was a lovely room with two doors – one which led to the rest of the house and the other that opened into the garden. It was also Payal’s favourite room. It had tall bookshelves and she spent hours there, reading all kinds of books. The bookshelves also had lots of little knickknacks. Her mother loved pretty things, and displayed them here along with the books. So there were beautiful pieces of pottery, dolls from wherever they had travelled, and of course wooden and clay animals and birds from all around the world.

     Once Owlie was moved to the library, strict rules were laid down for everyone in the house. The two doors were never to be left open – not at night, not in the day. Every night, Payal would leave the cage door open and put a plate of mincemeat on top of the cage. This was so that when Owlie flew out of her cage, she could also learn to find her food.
Explanation:
 
After a lot of discussion, they moved her cage to the library, which was Payal's favourite room. The library had two doors - one opened to the garden, and the other gave access to the rest of the house. The library had tall bookshelves, and Payal loved to spend time there, reading all types of books. The shelves also had a lot of decorative household ornaments. Her mother loved these knickknacks - pretty things like pottery, dolls, wooden and clay birds and animals - all collected from around the world, wherever they had travelled.
 
interior-1961070_1920.jpg
 
After Owlie moved to the library, there were strict rules for everybody in the house. Nobody should leave the two doors open - either day or night. Every night, Payal opened the cage door and put minced meat pieces on the top of the cage. This was to check whether Owlie is flying during the nights and also learn to find her food.
 
Meanings of difficult words:
 
Words
Meanings
knickknackssmall, colorful decorative ornaments
potterypots, dishes made of clay
Reference:
State Council of Educational Research and Training (2019). Term-1 English Standard-6. Owlie - Vijaya Ghose(pp. 101-104). Published by the Tamil Nadu Textbook and Educational Services Corporation.