In this verse, Jesus refers to the good news He wanted His disciples to hear. At the end of His death on the cross, Jesus would rise up again and ascend into heaven, at which time He would send the Holy Spirit, the Comforter, to help them and to be with them forever.
As Jesus said in His message to His followers, whoever sees Him has seen His Father. In addition, this Comforter was going to be the Holy Spirit of God, who was sent at Pentecost to help and protect the frightened followers. He was sent as a "Paraclete" and an "Advocate". Eventually, He would stay with each of them forever and indwell each of them permanently. 
Since the beginning of the Christian Era, the Holy Spirit has been the Comforter of all who have trusted Christ as Savior in the same way that Christ Himself had been to His little band of faithful followers. He is our Helper, Advocate, and Paraclete. He will be with us forever, and His love will abide in our hearts forever.

Dear Heavenly Father, thank You for sending the Holy Spirit to guide us and be our Comforter, to be there for us in every difficult situation that may arise in this life and to support us through it. Please help me to listen to His voice and follow His directions each and every day. 
In Jesus's name I pray. Amen.