There’s a Floating Text actor in the default library and when you hover over it, it just says “Draws 3D text in the world along with targeting line cues.”
There’s no documentation on this, and any google search is filled with using regular text render actor to make floating text.
Its also in 4.18, it seems like it’s a part of VR editor, it’s C++ coded and it in one of editor module, so it is not suppose to be in there and project probably not gonna package if you gonna use it. You can try to package with it to double check it, if it not package then go ahead and bug raport
Note that components are more important then actors, actor is only component container and also have code that controls those component together. So you can find actors that are just bundles of components but they aren ot much different then making them yourself, this floating text primerly have just component settings and some set text code: