The splash screen only appears on a pages with video backgrounds or parallax effect. These pages usually load considerable amount of time and the splash screen is valuable addition.
How to edit the splash screen:
The background of the splash screen is attached to an accent color in Customize > Global Styles > Accent 1
You can change the logo in 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.