English Idiom: Keep under wraps
If you keep something under wraps, you are keeping it hush-hush.
For example whenever a tech company is going to release a new device, such as a new smartphone, whenever an auto racing team designs a new aero package for their car or whenever a car manufacturer is developing a new model they always try to keep the original designs under wraps until the official release date.
They want to keep the new designs secret from both their competitors and customers.
Secrecy is of the utmost importance in business, national defence and office romances as well.
We all have things that we prefer to keep under wraps until we decide to let people know about it.