I played the trumpet couple of years in high school and getting back again. I stumbled across this in some notes. I can understand how it can be played on piano or guitar but is there any way it is also relatable to trumpet (b flat trumpet)?
the only understanding I can think of is that it is for two trumpet playing. But I am confused as I have also found in 'solo trumpet' notes.
That is one of the standard ways of writing wind instruments within a classical orchestra score.
Traditionally, wind instruments in the classical-age orchestra are paired, and, depending on the edition, single notes with single stems could be considered in two ways with the following convention:
In well written, explicit parts, unison notes are written with both up and down stems whenever the note has to be played by both musicians.
It's also up to the conductor, as always, to decide whether an explicitly written (or unspecified) "solo" part should be played by both musicisians.
In this specific case, without any further context, I'd say that the first B has probably to be played by both trumpeters, but you should better look for any indication in the beginning of the piece, the conductor's score or even the traditional performing practice (if it exists, otherwise ask to the composer/arranger/copyst/fellow player/conductor/teacher).
