1. number; edition; make; model; issue; part of that group
じゃあ、僕がその第一号になる。Then, I will be the first one.
2. sobriquet; pen-name
名前というよりは号なんだけどね。It's more of a pen name than a real name, though.
3. size (of printing types, canvases, knitting needles, etc.)
4. suffix attached to names of ships, trains, airplanes, etc.
この船はさくら号という名前だ。This ship is called the Sakura.