Client0 simply means the resource corresponds to a device with the client agent installed. Note that only the Clear Undiscovered Clients maintenance task (https://learn.microsoft.com/en-us/mem/configmgr/core/servers/manage/reference-for-maintenance-tasks#clear-undiscovered-clients) will ever flip this to 0 on an existing resource if it is currently 1.
Active0 means the site has received information from or about the corresponding device. Activity is briefly described at https://learn.microsoft.com/en-us/mem/configmgr/core/clients/manage/monitor-clients#bkmk_about.