Yati means a renunciant or monk who has given up worldly life to pursue spiritual awakening (moksha) in Jainism.

If you are asking about the yati (renounced life) of the Tri-Kankaras (Trikankaras)—the three principal Tirthankaras often referred to as Rishabhanatha (Adinath), Ajitnath, and Sambhavanath—their lives are described in Jain scriptures as follows:

• They all renounced worldly life, practiced deep austerities, and pursued spiritual realization.
• Each of them attained kevala jnana (omniscience) and taught the Jain path, establishing the creed for their era.
• The exact details of their renunciation, practices, and teachings vary slightly between Digambara and Śvetāmba r traditions. For example, the emphasis on certain rites, lifeways, and biographical details can be presented with different nuances in these two major traditions.

If you want, I can give a concise, tradition-specific outline for each of the three Tirthankaras (what they renounced, their practices, and their key teachings) and note where Digambara and Śvetāmbara accounts differ.