As Jesus paid the sin debt of the whole world the "middle wall of partition" was broken down as the veil in the Temple was rent from top to bottom. (Eph. 2:14; Matt. 27:51) From that moment on the Gentiles would not have to come through the Jews to receive salvation, but could boldly enter the throne of grace and obtain mercy for themselves. (Heb. 4:16) Note Jesus response addressed their inquiry and concerns. (Read carefully John 12:24-26).
Jesus' response is found five other times in the Scriptures which show the importance of His teaching. (Matt. 10:39, 16:25; Mark 8:35; Luke 9:24, 17:33) John does not record whether the Greeks heard Jesus or not. But Jesus' response revealed what was about to happen. Jesus responded with the illustration of a grain of wheat, stating if the seed did not fall into the ground and die it would not produce fruit. Clearly, He was speaking of Himself. The Greeks may have, like the Jews, thought that Jesus was presenting Himself as the civil Redeemer of Israel who would conquer the Romans. However, Jesus did not speak of His forming an army or beginning a great civil conquest, but rather they He would soon die. Those that would follow and serve Him, He said if they loved their life they would lose it, and if they lost their life for His sake they would find it. The Greeks as proselytes [recent converts] were following God and Jesus was saying that as the Messiah those who would receive eternal life would have to love Him more than their lives. In other words Jesus was not offering a worldly kingdom, but a spiritual one. Jesus showed He was fully aware of the coming trials, beatings and agonizing crucifixion that faced Him. He was setting the example before them.
In response to Jesus' proclamation and prayer, God the Father answered immediately from heaven saying ". . . I have both glorified it, and will glorify it again." The Father by speaking from heaven at this shows the intensiveness of the moment and the magnitude of Jesus' commitment to the will of the Father. We cannot fathom the love of the Lord for us that would endure the penalty for our sins in order that we might be able by faith to receive His grace, mercy, forgiveness and eternal life. God the Father says I glorify you now and will glorify you in your coming crucifixion and sufferings for the sins of the world.