Some time SharePoint column header needs to be quite long, but the content of the column is only a
few pixels wide, so loads of white space and horizontal scrolling required to see the rest of the content.
To avoid the long column to be shorten we can use this below css method to avoid this long column issue.
You can use SharePoint Designer to add the style to SharePoint list view page to make the column header multiple rows for long text.
Place the style under PlaceHolderMain tag like the capture below,
<style type= "text/css"> .ms-vh2 {white-space: normal} </style>