What is white space?

White space or negative space is simply unmarked space in the design. It is the space between the layouts, lines of paragraphs, between paragraphs, between different UI elements and so on. White space does not literally mean an empty space with a white background. It can be of any color, texture, patterns or even a background image.

“White Space in design composition is same as use of Silence in a musical composition. Without proportionate use of Silence, music is unstructured; some may call it noise. Similarly, without White Space, design is unstructured and difficult to consume”

https://blog.prototypr.io/importance-of-white-space-in-design-5a40c0e65bfd