These people mentioned were probably Greek speaking Jews from another country. At any rate they were coming there to worship so they at least would be prosolites. David had mighty men who were Gentiles left in the land of Canaan.
Another interest is the two disciples who these people talked to, first Philip then he talk to Andrew. Philip brought Nathanael to Christ. Andrew is mentioned three times in John's gospel. First bringing his brother Peter to Christ. Then finding the boy with 5 loaves and two fish. Jesus feeding the multitude and now it seems he is a people person.
Now they tell Jesus and what does He say? They were nearing the cross so Jesus simply says, "The hour is come for the Son of Man to be glorified." Could He be saying that all things must be in their place and that He would be the precious seed that would have to fall in the ground to bring forth fruit.
Next Jesus said that the disciples would also be seed falling into the ground to bring forth fruit. All but John (Judas not included) met violent deaths. We now can do evangelism so that not to exalt ourselves, we too have to be a type of seed falling into the ground in order to bring forth souls as fruit.
In verse 26 Jesus said if anyone serves me let Him follow me. Where was He going? To the cross. Typically that is where I need to go too.