what is frequent and pitch?

Answer 1

I think you mean frequency and pitch.

A is a note and it's frequency is 440. That means to produce an A an instrument must make vibrations travel in the air at the rate of 440 waves per second

The waves are measured in Hertz or waves per second. Other notes are different frequency, but A an octave below A 440 is 220 hertz and an A above A 440 is 880.
The notes are the pitches, A B C D E F G and the sharps an flats are the pitches heard in music.

Below is a diagram of a piano keyboard and the corresponding hertz values: