Scale Degrees

Every note in a scale has a special name for it. These special names are called scale degrees.

The first and last note is called the tonic. They are the same name simply because it is the same note but different octaves.
The second note is called the supertonic. In Latin, "super" means above.
The third note is called the mediant. You might have heard mediant in math before and know that it means middle. This mediant is called that because its in the middle of the tonic and the dominant.
The fourth note is called the subdominant. In Latin, "sub" mean below ergo its the note below the dominant.
The fifth note is called the dominant.
The sixth note is called the submediant. This is the middle of the subdominant and upper tonic.
The seventh note is called the leading tone.

Any major scale can be formed using a certain formula. This formula will help to know if the next note in the scale is half a step high or a whole step higher.
The formula is:

Whole step Whole step Half step, Whole step Whole step Whole step Half step

For example in the C Major scale:

C to D          D to E          E to F       F to G          G to A          A to B          B to C
Whole step   Whole step   Half step   Whole step   Whole step   Whole step   Half step

C = tonic
D = supertonic
E = mediant
F = subdominant
G = dominant
A = submediant
B = leading tone