Hello Bharath

Counselling schedule means it is generally a procedure through which either individual institutions or groups of institutions take admission of student across the country based on their rank and merit. It is conducted in two way online counselling and offline counselling. Due to enhancement of technogy most of the institution conducting it online. 

In case of jee advanced it is conducted by (JOSSA) ie. Joint seat allocation authority for admission to various engineering courses in IITs, NITs, IIITs across the country. Through this about 35k student got admitted to the finest institute of the country. 

Good luck!

Feel free to ask if you have any further queries.