No, it's not. And your question isn't right either. It should be "Is this correct English grammar?"
"My hobby is reading books ..." that's fine.
You can add, "but I also take part in some sports such as swimming and jogging." You can't say that a hobby is 'sometimes' doing something. You could say, "My hobbies are reading, swimming and jogging."
The rest is not right at all.
You could say, "The rest of my time is spent helping my parents in their shop," or wherever their business is.
If you say 'selling' you'd need to say what they're selling.