Bizarrely means “in a very strange way.” You use it when something is not just a bit odd, but so unusual that people stop and think, “Wait, what?” It can describe how someone looks or acts: a person may dress bizarrely, speak bizarrely, or behave bizarrely. Though actually, a lot of the time it does not sit next to a verb of manner at all. Speakers often put it at the front of a sentence to mark a whole fact as weird: “Bizarrely, the shop was empty at noon.” That use is close to “oddly” or “strangely enough,” but bizarrely feels stronger and a little more colourful — you can hear the raised eyebrow. It is everyday English, fine in speech, messages, and newspapers. It is less at home in very stiff formal writing, where people may prefer strangely or unexpectedly. It always keeps that sense of “this does not fit what we expected.”