If your manager has granted you delegate access, you have the ability to act "on behalf of" him or her. Depending on exactly how much access they've given you, you may be able to respond to meeting requests, send out meeting invitations, and handle their email messages.
By default, everyone who has a Cornell Exchange account has limited access to your calendar. As they create a meeting invitation, they will be able to see (on the Scheduling Assistant tab) whether you are free or busy, but they won't be able to see any other information about your schedule (such as the meeting title, who is invited, or where it's taking place).
As you create a meeting invitation you are able to see whether others are free or busy, but you aren't able to see any other information about their schedule (such as the meeting title, who is invited, or where it's taking place) unless the other person has chosen to share their calendar with you.