What does “keyof typeof” mean in TypeScript?

Explain to me what keyof typeof means in TypeScript

Example:

enum ColorsEnum {
    white="#ffffff",
    black = '#000000',
}

type Colors = keyof typeof ColorsEnum;

The last row is equivalent to:

type Colors = "white" | "black"

But how does it work?

I would expect typeof ColorsEnum to return something like "Object" and then keyof "Object" to not do anything interesting. But I am obviously wrong.