Idle is an adjective which means inactive
It is also used as a verb in the same sense, meaning spending time without doing anything.
1. The machines lying idle are causing great losses to the company.
2. He is jobless, and thus is usually idle at home.
Idol is a noun used to describe a person who is greatly admired and loved.
Also, it is used to describe an image or a representation of god.
1. The idol of Lord Krishna is made up of gold.
2. Sachin Tendulkar has emerged as an idol for millions of young sportsmen.