Shiksha is a Sanskrit word, which means "instruction, lesson, learning, study of skill". It also refers to one of the six Vedangas, or limbs of Vedic studies, on phonetics and phonology in Sanskrit.
A page from the Yajnavalkya Shiksha manuscript (Sanskrit, Devanagari). This text is also called Vajasaneyi Shiksha and Traisvarya Lakshana.