Camille,I learnt this from you and I want to know if I'm right:pitch and key are not the same. Pitch is how high or low a note is and key is a set of pitches. I'm I right?

Also Camille,what is a note? I know that a pitch is how high or low a note is but I don't know what a note is

That's correct! A note technically has pitch and rhythm (duration), for example, an eighth-note or a whole note. However, many people use the terms pitch and note interchangeably. They'll say "this note is C" without specifying the duration/rhythm. 

Okay thank you

And the word "key" I said is a set of pitches is the musical key right and not the physical key right?

That's correct!

Thank you Camille,God bless you!

Glad to help!