It is a VR player app. You can use this app to watch 360 VR videos. You need to transfer a VR video between your iPhone and Mac(PC) or download it from a website. You can also use iCloud Drive.Then past videos to this app folder in your Files app.
Open this app and close it -> Open your Files app -> Past a VR video to this app folder in your Files app -> Tap the reload button and play the video.