Typically it is called an "Overture."
An overture is an orchestral piece at the opening of an opera, suite, play, oratorio, or concert. It is usually an instrumental composition which serves as an introduction to an extended work.
It's when you just play the music of a song and don't sing.
It was the opening sequence of Mozart's piece "Eine Kleine Nachtmusik"
a. an elaborate instrumental composition in three or more movements, similar in form to a sonata but written for an orchestra and usually of far grander proportions and more varied elements. b. an instrumental passage occurring in a vocal composition, or between vocal movements in a composition. c. an instrumental piece, often in several movements, forming the overture to an opera or the like. d. a concert performed by a symphony orchestra. e. anything characterized by a harmonious combination of elements
The ritornello is a recurring instrumental passage in a Baroque musical composition that typically alternates with solo sections. It serves as a structural anchor and provides thematic cohesion throughout the piece.
an instrumental piece
It is basicly a small sonata (an instrumental piece )
A bagatelle is a short and light piece of music, usually written for the piano.
"A piece of choreography" or just "a piece"
A Schubert composition is a piece of music that was written by Schubert.
There are no lyrics. It's an instrumental piece.
An étude (a French word meaning study), is an instrumental musical composition, most commonly of considerable difficulty, usually designed to provide practice material for perfecting a particular technical skill.