If you don't want all employees who have access to your Outlook calendar to see a specific meeting subject, you can hide the subject from them.
How to do this in Outlook
When creating an appointment or meeting, select the Private category in the Categories group on the Appointment or Meeting tab.
All employees who do not have access to your private appointments cannot view the subject or the contents.
Note: Employees with access to the Private category can still view the meeting title.