The purpose of this plugin is to manage conflicts between jobs.
The Exclusion plugin allows you to assign resource names to jobs in Jenkins. The plugin will ensure that jobs sharing a same resource will not be executed at the same time. The resource name is a semaphore. With the second part of the plugin you can, in an administration panel, see the list of resources configured in each job, see when a resource is allocated and, thanks to the release button, you can release a resource currently used.
See: Exclusion-Plugin