Rozan is the true name of Godzilla, and is in fact an alien creature that originated from Godzilla Planet. Having contracted diabetes, her dying body washed ashore upon Japan, where scientists looked at her internal organs, including her brain. After an attempt to psychically communicate with Rozan, the humans learn of her plight and are requested to help her get her home. Thus against the protests of the victims of Rozan's rampages, the kaiju is converted into a rocket and sent off into space, where she and her child Lilin would make the trip back home.
Note: As A Space Godzilla was originally intended to be the 16th Godzilla film, it's possible that Rozan would share the same feats and abilities as Showa Godzilla.
Credit to the listed feats goes to this respect thread on Reddit.