Reuters
While it's unclear what, exactly, this event will entail, we do know it will be hosted by Dave Limp, the Senior VP of Amazon Devices and Services - hinting that any news will likely have to do with the Amazon Echo line of smart speakers, as well as the Amazon Alexa smart voice assistant which powers it.
It's a safe guess that Amazon could be announcing a proper second version of its flagship Amazon Echo speaker, which hasn't gotten a significant upgrade since its introduction in 2014. Otherwise, the Financial Times recently reported that Amazon is working on Alexa-powered smart glasses that would use bone conduction technology to talk to you without your having to wear any kind of headphones, though the report mentioned the smart glasses weren't scheduled to be announced at the Wednesday event.
Regardless, keep watching Business Insider for more news and updates from Amazon's big event.