Hey there

JEE mains is an exam conducted two times in a year previously once. This exam is conducted for admissions into nits, iiits, gftis and many more engineering colleges in India. It has got two papers one for BTech and other for architecture. One who qualify JEE mains are allowed to sit in JEE advanced which is one of the toughest exam in the world and if you clear the exam you will have chance to get admission into iits, IISC, iist etc.

Check about JEE mains

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/exams/jee-main&ved=2ahUKEwjyztLdktPkAhUc63MBHSSNA8gQFjAAegQIARAB&usg=AOvVaw1k3rMyr-Osb0qy4gsPfOaR

Check about JEE advanced

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/exams/jee-advanced&ved=2ahUKEwin_JzhktPkAhVv_XMBHVZwB3UQFjAAegQIAhAB&usg=AOvVaw27auQU717YYuHGYaNfL5SD

Good luck