It means the tone is 1/2 step above the note given. A full step would be to go from A to B, therefore a half step would be A sharp.
If you are talking sheet music, a sharp sign is as it always is, a # if I am not mistaken.
Its a kind of note in music. Its also in the G-scale of g sharp it is on the grand staff on piano.
The music gets louder
pianissimo!
slowly!
Slow
In musical terms, rinforzando means reinforced.
That's not a standard term in music.
Play loudly!
X is a double sharp, X G (G double sharp) for example would be the enharmonic equivalent of A. If the "ball" of the note on the music is replaced by an x, then that would mean to "ghost the note."
Example: If note in question is a sharp, then the "x" changes it to a double sharp.
It means "smooth and connected".