You can control whether your clients can see the schedule on a project-by-project basis. To check or change the setting for a project:
Go to your Dashboard > click on the "i" info icon for your project > "Edit project setup".
On the project's Setup page, you will see the option for changing whether the clients can see the schedule calendar.
If this access is enabled, your clients will be able to see the calendar view of the project, with the task names and percent completion. They will not see your assignees, public/private notes, or file/photo attachments. Note that they will also only see the currently published schedule, so if you have been working on a schedule and saved your changes to a new draft, those will not be reflected on the client's view.
If the clients cannot see the schedule, they will still see a list of the milestone names from your Published Schedule, with checkmarks next to any that are 100% complete. However, the clients will not see any dates for these milestones.