The splash screen only appears on pages with video backgrounds or parallax effect. These pages usually load a considerable amount of time and the splash screen is a valuable addition.
How to edit the splash screen:
The background of the splash screen is attached to an accent colour in Dashboard > Appearance > Customize > Global Styles > Accent 8
You can change the logo in Dashboard > Appearance > Customize > Site Identity > Splash Screen Logo
How to enable/disable the splash screen:
You can enable or disable the splash screen in the page's local Vamtam options.