Typically this is a series of movements with the Feet, that is ascribed to a Follower, but a Lead can do them as well, which is done with the feet outside of the music, but in relationship to what has been led or followed to ‘dress up a bit‘ what was done.
In modern Tango, you can’t talk about Embellishments without talking about Adornments. So there is a need for distinction beween the two: The embellishment is a physical decoration of the movement that is being invoked. 9 times out of 10 it doesn’t necessarily follow a musical element at all, hence the reason it’s not tied to the music but rather to the led or followed movement and the need for the distinction. If it were tied to the music, it would be an Adornment!
(See also: Adornment)