To unveil something means to show or reveal it for the first time.
When people talk about unveiling something, they usually mean that someone is going to share or display it publicly. For example, a new painting might be unveiled at an art gallery so everyone can see it. Sometimes, when a famous statue or monument is finally opened after being hidden or covered up, it's also described as being unveiled.
To remove a veil from; to uncover; to reveal something hidden.
