means by

[Flyby]

i do not understand the meanding of the sentence in bold.

[ Every jazz player knows what he or she menas by improvision. And all writers know what they mean by improvision.]

[Raymott]

i do not understand the meanding of the sentence in bold.

[ Every jazz player knows what he or she menas by improvision. And all writers know what they mean by improvision.]

I think you mean "improvisation".

[Anglika]

i do not understand the meanding of the sentence in bold.

[ Every jazz player knows what he or she means by improvisation. And all writers know what they mean by improvisation.]

To improvise in the context of music means to play spontaneously and without preparation; in the context of writing, it means to use what is available.