In music you can assume that all notes but two have a sharp and all notes but two, have flats
In one direction you have sharps . In the other direction you have flats. It all matters

I will use a piano as the example because most people are familiar with the appearance of one, but not everyone can just go look at a trumpet.

The notes of a piano

Notice that there are Seven notes called “Natural Notes”. I have heard them called Natural tones also, but not for this.
Also notice there are only five accidentals (sharps and Flats).
The change from one natural to the next natural note is called a whole step. The change to a sound half way between two natural notes is how you achieve the semitones. The semitones are the sharp notes and the flat notes that lay between two naturals. If you are raising a note by a half step, you call that note the sharp of what ever note you just raised. So if you are raising an A note, then you will call this note an A# or A sharp. and the same if you are lowering notes. If you are lowing a note from a B, then you will consider this a Bb or B flat.

There is no such thing as a B sharp, no C Flat, There is no such thing as an E Sharp or an F Flat
This will explain why on a piano, most of the white keys have a black key on either side, and some only have a black key on one side but not the other side.

The notes just repeat themselves at a higher or lower frequency but the pattern is the same. so the 8th natural note is considered the next octave higher than the previous.
In other words, an octave is 8 whole steps higher or lower away from your highest or lowest note, depending on where you are going. If you are looking for an A that is higher than the A you just played, look 8 whole steps in the direction that produces a higher sound than the A in question.5 you now understand why there are 12 frets for each octave on a guitar.