Oh, dude, that's easy. You call it a "solo piece" or a "solo composition." It's like when your friend decides to go solo in a boy band - they just want all the spotlight to themselves, you know? So yeah, it's basically a piece of music written for one instrument to show off its skills without any distractions.
A note.
It means someone individually plays a short piece of music (usually the leader), and the rest of his/her band replies to it by doing another short piece of music.
A short piece of music played in honor of a person or event is call a "Baroque".
The official term is "diegetic music", but it's quite academic and archaic. "Source music" is the more common term.
Never call a classical piece of music a song. It's a piece, and song has lyrics. And probably his Clarinet Quintet or his Sextets for Violin and piano.
A note.
Ostinato
It means someone individually plays a short piece of music (usually the leader), and the rest of his/her band replies to it by doing another short piece of music.
double line
It was written by Wolfgang Amadeus Mozart, a composer in the Classsical Era. For this reason, you could call it a classical piece.
A short piece of music played in honor of a person or event is call a "Baroque".
That's called a duet.
It means someone individually plays a short piece of music (usually the leader), and the rest of his/her band replies to it by doing another short piece of music.
A person who plays a musical instrument for a living is typically referred to as a musician. Musicians may perform solo or as part of a group, and they often specialize in a particular instrument or genre of music. Some may also compose or arrange music in addition to performing.
"Piano" in music means "softly", from the Italian. The instrument we call the piano has a full name of "pianoforte", meaning soft, loud. The name reflects the wide range of volume that the instrument has.
"Playing by ear" describes the ability of a musician to to reproduce a piece of music without having observed another musician playing the piece.
The Last Post is a British bugle call that is often played at military funerals and remembrance services. It is not a written piece of music attributed to any specific composer, as it is a traditional bugle call used in military ceremonies.