Now Jesus is praying specifically for Jesus's own disciples. In particular, Jesus talked about how at that time, he "do[es] not pray for the world but for those whom [the Father] had given [Jesus]" (17:9). Remember that Jesus still loves the people of the world (as noted in John 3:16) -- but in context, Jesus's prayer is specifically to the Father and for the disciples, who are not only disciples of Jesus but also disciples of God. This is because the disciples have accepted Jesus (while not everybody in the world does), who was sent by the Father.
Next, Jesus talks about how he is "no longer in the world" but the disciples "are in the world" (17:11). What did Jesus mean? First off, we know that Jesus started in heaven and would later depart from Earth and that unlike the world, Jesus is free from not-good mistakes called "sin". Additionally, we know that the disciples were born on Earth and that they are still susceptible to sin. Thus, it's possible that Jesus is referring to the origin or that later on, the world would reject Jesus (as seen with the crucifixion). It's also likely that Jesus is referring to the future where he would not be on Earth physically, as noted by the ERV, ICB, and NIV translations.
However, in spite of differences in susceptibility to sin as well as origin, the disciples (aside from Judas) accepted Jesus. Jesus told the Father that He "kept them in [the Father's] name" and that "none of them is lost except the son of perdition" (17:12). Jesus's actions fulfill Scripture in that the description on who Jesus would be is accurately described -- especially with his role on Savior. Now Jesus proclaims that he "come[s] to [the Father]" and speaks some things in the world so that "[the disciples] may have [His] joy fulfilled in themselves" (17:13). Jesus cares about the disciples and wants them to have a fulfillment of joy, even when bad things are about to happen.