Safe Area is a layout guide (LINK).
The layout guide representing the portion of your view that is unobscured by bars and other content. In iOS 11+, Apple is deprecating the top and bottom layout guides and replacing them with a single safe area layout guide
Since iPhone X’s status bar height is different from all previous iPhone, this causes Label-A to be mispositioned below the status bar.

To fix this, we will need to use “Safe Area Layout Guides” that being introduced in Xcode 9 interface builder.

For more about SAFE AREA you should read this LINK