Well, for a start, we have the balance if the scriptures written after Jesus. We have revelations about the peculiar nature of the church (the bride of Christ), which was previously not revealed...a mystery, but now revealed. We have reaching about the end times; about church governance; about roles if leaders, elders etc. The holy spirit also clearly aided the disciples, just as Jesus said, eg they wiould have the right words to preach and defend themselves. (just compare how unlearned peter spoke before and after Pentecost...! A miracle just there.)
I could go on.
But the hs also lives on today in my heart, guiding me, teaching me etc