In complex computational models, it is sometimes necessary to keep multiple files open at the same time. If you need some of them only for working formulas and general calculations, then you can temporarily hide them, so as not to be confused in the abundance of windows.
By the way, this setting is saved with the file. When you next open the book will be immediately hidden. But, of course, at any time it can be re-displayed in the appropriate window.
For more details on the ranges, see the article.
