12 Notes in Music
Western music uses only 12 different notes. They repeat over and over in higher and lower versions.
These are: A A#/Bb B C C#/Db D D#/Eb E F F#/Gb G G#/Ab
Every note is a half-step up from previous, and we can use either sharps or flats. A# and Bb mean the same thing. B and E have no sharps.
After G#/Ab it goes back to A again, just higher.
You don't need to memorize them all today. Just know that there are only 12.