"Status candidates" are current or former federal employees who have worked in the competitive service, in a permanent appointment for a total of three years of qualifying service. Sometimes this is also called having 'status' or a 'career appointment'.
If you have status, you're eligible for jobs that are open to Federal employees - Competitive service. These are also known as merit promotion jobs.
Look for the This job is open to section in the job announcement. If the job lists “Federal employee-Competitive service”, you're most likely eligible. You can also look at the Clarification from agency or the Who may apply sections—it might say “Status candidates” or "Merit promotion".