From the Microsoft Documentation:
"Microsoft® Windows® Script Host is a language-independent scripting host for ActiveX® scripting engines. It brings simple, powerful, and flexible scripting to the Windows 32-bit platform, allowing you to run scripts from both the Windows desktop and the command prompt.
Windows Script Host is ideal for non-interactive scripting needs such as logon scripting, administrative scripting, and machine automation."
In other words:
It gives you useful objects to fiddle with, in various languages.
Just as ActiveServerPages introduce intrinsic global objects to the ScriptingEngine per request, so to does WSH. For example, the "WScript" object in WindowsScriptingHost is somewhat equivalent to the "Server" object in ActiveServerPages in that it provides a "CreateObject?" method to which a ProgId of a ComComponent may be passed for instantiation.