View formatting is sued to customise how views in SharePoint lists and libraries are displayed.

View formatting is sued to customise how views in SharePoint lists and libraries are displayed. To do this, a JSON object is created that describes the elements that are displayed when a row is loaded in a list view and any styles to be applied to those elements. View formatting does not change the data in list items; it only changes how they're displayed to users who browse the list. See documentation.