That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me.
22 And the glory which thou gavest me I have given them; that they may be one, even as we are one:
23 I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me.
Apologists for Islam tells us that these verses are speaking of a oneness of purpose. This is rubbish and is just an example of them imposing their ideas and agenda on others, as usual.
The key to interpreting this verse is given by Jesus in John 14 v
17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
18 I will not leave you comfortless: I will come to you.
19 Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also.
20 At that day ye shall know that I am in my Father, and ye in me, and I in you.
Jesus is going and leaving the disciples but he is coming again in and through the Holy Spirit. Through the Holy Spirit the disciples, the Father and Jesus are all one as he describes in his priestly prayer in John 17.
I would say that the glory that Jesus speaks of in verse 22 of chapter 14 is the Holy Spirit himself.