"You [God the Father] gave him [Christ] authority over all humanity, so that he might give eternal life to all those you gave him. And eternal life means knowing you, the only true God, and knowing Jesus Christ, whom you sent."

(John 17.2-3 GNB)

The word "eternal" means "continuing forever" (Cambridge Dictionary). Many people want to live forever. Or they want to avoid hell and, instead, forever be in heaven after death.

But in the passage above, eternal life refers to "knowing" God and Christ. Knowing God and Christ, through the help of the Spirit, is what we receive for trusting Christ.

Knowing God and Christ is eternal life.