What is a celests?

Answer 1

A celesta (also known as a celeste) is a keyboard instrument in the form of a small upright piano, and was invented by Auguste Mustel in 1866; metal plates suspended over resonating boxes are struck by hammers and sustained after the manner of the piano action. Its compass is five octaves from c; it is written an octave below sounding pitch, producing a distinctive chiming sound. Tchaikovsky included the celesta in The Nutcracker (1892) as did Bartók in his Music for Strings, Percussion and Celesta.

The proper name Celeste is also from the Latin word caelestis, for "sky" or "heavens".

Answer 2

Perhaps you mean Celeste - it is a percussion keyboard instrument consisting of a set of steel plates.

Or it could be a feminine given name deriving from a Latin word meaning heavenly.