Allows Super Admins to control which plugins are visible to admins of a given site within a multi-site WordPress environment.
If you are a Super Admin, navigate to the plugins page in the admin section. Each plugin will have its visibility status (i.e. 'is Visible' or 'is Hidden'). Next to this is a link ('make visible' or 'make hidden'). Clicking on this link will change the status of this plugin in the current site.
Navigate to the Plugins page in the 'Super Admin' menu. From there, find the plugin in question and click on 'make Visible'. Plugins visible to the Network will be visible on every single blog on your server.
Plugins that are 'Hidden to the Network' will not be visible on individual blogs, but they can be made visible on a blog by blog basis.