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.