Update: Bixby's expanded language support was indeed briefly alluded to during the Samsung Unpacked Event.
Bixby is Samsung's own take on the voice-control assistant, and is baked into the Experience and One UI launchers on the OEM's mobile devices by default. It may be seen as less of an asset to many users, as it takes up its own hardware button on many phones. Besides this, it supports far fewer languages compared to other virtual helpers such as Google's own Assistant.
In fact, Bixby has only ever supported three languages: English, Korean and Mandarin Chinese. However, XDA has reported that the latest version of this assistant, 2.0, now also supports German, Italian and Spanish. The outlet initially uncovered this possibility as part of the debug menu hidden in the app's code. Subsequently, it has noted that these new language features are being rolled out.
This most recent development in Bixby 2.0 have been reported on the day of Samsung's latest hardware launch (20 February 2019). This event, known as Galaxy Unpacked, may mention its new functionality at some point. However, it is more likely to focus on the Galaxy S10 line and Galaxy Fold instead.