A man stepped before the judge. He had broken the law. "Guilty," cried the judge. "Your sentence is death." The man was under judgement. This means he was guilty and waiting to be punished.
God says that all who do not believe on Him will come into judgment. They are guilty of sin (breaking God's laws). They will have to be separated from Him forever. The Bible calls this punishment death.
But those who believe that Jesus died in their place will NOT come into judgement. The very moment you rceive Jesus as your savior, God can say to you, "Not guilty." You no longer have a death sentence. You will never have to be separated from God. You receive everlasting life.
How long is everlasting life? (for ever and ever and ever and ever..)