Octaves & Flat Major Scales

An octave is going from one note to the next higher note of that letter. An octave is eight notes. Playing an octave is a scale depending on the flats and sharps. All major scales start on the letter of its name.
For example, your basic C Major scale:

The C Major scale has no sharp and no flats. When a piece of music has no sharps or flats you would say, its in the key of C. Learning the letter names of the scales is similar to learning the note letter names.

Learning the flat scales first will make it easier to learn the sharp scales later.
The order of the flats are: B-E-A-D-G-C-F
Like I said with making up words to remember the order, a popular one for the flats is BEAD Greatest Common Factor. Another could be BEAD Great Chicago Fire.
All the flat scales except F have flat in the name.

F Major has 1 flat: B-flat

B-Flat Major has 2 flats: B-flat and E-flat

E-flat Major has 3 flats: B-flat, E-flat, and A-flat

A-flat Major has 4 flats: B-flat, E-flat, A-flat, and D-flat.

D-flat Major has 5 flats: B-flat, E-flat, A-flat, D-flat, and G-flat.

G-flat Major has 6 flats: B-flat, E-flat, A-flat, D-flat, G-flat, and C-flat.

C-flat Major has 7 flats: B-flat, E-flat, A-flat, D-flat, G-flat, C-flat, and F-flat.