Before any modification, look up at the admin first.

In admin => Configuration => My Store

Code:
Show Category Counts  	true

Show Category Counts - Admin  	true
In admin => Configuration => Layout Settings

Code:
Categories Separator between links Status  	1
Categories Separator between the Category Name and Count 	->
Categories Separator between the Category Name and Sub Categories 	|_ 
Categories Count Prefix 	 (
Categories Count Suffix 	)
Categories SubCategories Indent