Re-launching a process means publishing a new version of the same job, with a clean selection process (without the information of the professionals who originally applied).
If you have a subscription plan, you will be able to access the applicants' information immediately. If you do not have a subscription, you will have to unlock your job to access the applicants' information.
To re-launch a process you must go to your closed processes from your jobs panel and click on the "Re-launch process" button.