it's sol-fa syllables
Sol-Fa syllables are used to represent the tone of a scale. Most of the time it is used in vocal exercises. The Sol-Fa syllables are:Do - CRe - DMi - EFa - FSol - GLa - ATi - BDo - C
The set of syllables do, re, mi, fa, sol, la, and ti, used to represent the tones of the scale.