The word "Freewill" doesn't exist in the Bible but the concept does exist. The Bible doesn't spell out the term "Freewill" clearly and hence doesn't provide any clear definition of what freewill is.
The Freewill theology has a long history, at least 2000 years ago, discussed by philosophers. Many Christian theologians have studied this and made many theories on it. One of the first being Augustine and many debates were held among theologians on the topic of Freewill.
There are many instances from the Bible to explain what freewill is. Let's see few examples.
For God so loved the world that he gave his one and only Son, that
whoever believes in him shall not perish but have eternal life. (John
It is clear from this verse that anyone, who believes in Jesus Christ is promised an eternal life. This means that we are given freewill to accept or deny Jesus Christ.
Another example is Adam and Eve eating the forbidden fruit. God gave them orders not to eat the fruit and told them that they will die as a result, but when they were about to eat it, God did not stop them, though God was aware of it because He is omnipresent. God did not interfere in there choice making. God allowed them to choose death, even though God knew that it would result in the death of His one and only Son Jesus Christ.