Well...the passage does not teach us in what way they are "one"...does it?
But the passage DOES teach us more about it. The passage teaches us how the Jewish audience understood it:
Now: after the audience told Jesus that they thought he was "making himself out to be God", how did Jesus respond? Did he assure them, "No, no, you've got it all wrong. That's not what I meant at all. I meant that were are one in purpose only."
No, that's not how Jesus responded to the accusation that he had made himself out to be God. Instead he responded in this way:
And though that is someone vague and unclear (perhaps intentionally so), one thing is certain: ***in response, Jesus did not deny that he had made himself out to be God***.
This *strongly* suggests that Jesus' meaning was, in fact, "making himself out to be God". If that was not his meaning, if that were contrary to his meaning and blasphemous to boot, surely he would have been powerfully motivated to assure the audience that he meant no such thing?