When music moves from one key to another, it 'modulates'. Modulation is that process.
The 'style' a note is played in. I'm finding this harder to define, but think short, sharp notes vs. long, smooth ones. Articulation is the style a note is played in.
Sharps, flats and naturals which pop up through the music, and are not part of the key signature. Below, the A# is an accidental. The following A natural is labelled as a 'courtesy accidental', as by the rules of music, the A# accidental is removed at the bar line, but the composer has added a 'not strictly necessary' accidental, as a reminder to the player.
How a passage of notes is played together. Music isn't just notes that follow each other - it's written as phrases - passages of notes which work together, and places where natural breaks in the music should come. These aren't always written in any way, and can rely on the performers interpretation of the music.
Take "Twinkle Twinkle Little Star":
There are no actual breaks (rests) written anywhere in that music. However, from the shape of the notes (they way they go up and down), and the position of the longer notes, a player could play this piece with 3, 4-bar phrases, and control the 'flow' of the piece to accentuate this, through the use of dynamics, or following a less strict time.