When a job announcement closes, it means you can no longer apply to the job.
Job announcements can close in one of three ways:
Closing date
Most job announcements close on the closing date that's in the job announcement.
Open continuous
Some job announcements stay open indefinitely. You can submit your application at any time, but the job announcement will usually include a date (or several dates) when the hiring agency will select a group of applicants to review.
For example, the job announcement may say it will review applications on July 30, August 30 and so on. If you submit an application on August 1, the hiring agency will review your application starting on August 30.
Applicant cut-off
Some job announcements close when the hiring agency receives a certain number of applications. If the 'cut-off' number is reached during the day, the job announcement will usually close that night at midnight.
For example, a job announcement may say it will close after the hiring agency receives 200 applications. If they receive 200 applications by 1:30 p.m. ET, the job will close that same day at 11:59 p.m. ET.