16:26-28 What does Jesus mean by what He says here?

Jesus means here that now that the disciples would have direct personal access to the Father through His name, He would no longer need to pray on their behalf - they can ask for themselves (CP V23).

Here Jesus authorizes His disciples to use His name for anything they desire of the Father. This is the believer's power of attorney. We can ask for, or do anything on earth in Jesus' name in accordance with His word knowing that it will be confirmed in Heaven (CP Mt 18:18-20; Ro 8:32; 1Jn 3:19-22; 5:14-15).

The Father will do it to show His love for believers because of their love for Jesus (CP Jn 14:21-23; 2Cor 1:19-20).

None of this though negates Christ's intercessory role in Heaven with the Father for believers (CP Ro 8:34; He 7:25; 1Jn 2:1-2).