to bring out of hiding into the open: to make something (or someone) visible, known, or plain that was concealed
This verb pictures a single motion: taking what was hidden and bringing it into full view. It is built on the adjective for "visible, out in the open," so at its heart it always means moving something from concealment into sight or knowledge. The New Testament puts that one motion to work in three closely linked ways.
Most often it is about disclosing truth or character that people could not see before: God making his nature plain, the long-kept secret of his plan finally announced, a person's inner reality brought to light. From there it stretches to a person actually stepping into view, which is why it becomes a favorite word for Jesus coming into the world, showing himself alive after the resurrection, and appearing again at the end. And because bringing something into the open also tests it, the verb can carry the edge of exposure: deeds, motives, and people shown for what they truly are.
The three senses are not separate words but one idea seen from different angles. Whether the thing brought into the open is a truth, a person, or a hidden character, the core never changes: what was concealed is now manifest. This is why English translators reach for a whole cluster of words for it, from "reveal" and "make known" to "appear" and "show."