The Father, The Son, and The Holy Spirit.

Acts 7:55
    “But he, being full of the Holy Spirit, gazed into heaven and saw the glory of God, and Jesus standing at the right hand of God.” NKJV

    While Stephen’s judgers were furious at him, he did not falter, but his eyes wandered up to heaven where he saw a vision from God. It is interesting to note, at this moment in time, all three members of the trinity were immediately present and visible to him.
    Seeing God alone is a very significant thing, but Jesus and the Spirit were there as well.
    It is unclear to me why they chose to reveal themselves physically to him just then. Perhaps it was a last attempt to sway the crowd, or to give Stephen courage for the read that lay ahead.
    And on top of that, it could have even been meant for us. It is proof that even when the whole world, it seems, forsakes you, God will not forsake you.
    He will be faithful to us even to death and beyond.
    The application then is to know that God will be faithful, and that, even in the midst of great turmoil, look up to God, for He will be there with you.