What is the meaning of Sixth?

The ordinal form of the number six.

The person or thing in the sixth position.

One of six equal parts of a whole.

The interval between one note and another, five notes higher in the scale, for example C to A, a major sixth, or C to A flat, a minor sixth. (Note that the interval covers six notes counting inclusively, for example C-D-E-F-G-A.)

to divide by six, which also means multiplying a denominator by six

Source: wiktionary.org