Click into Settings > Spaces and select the space you wish to edit. Under "Visibility" you can decide who will be able to view your space.
You have three options here:
All users can see the space. Select this option if you would like all users that have basic access to see your scheduler to be able to see the space.
Users with certain tags. If you would like only users with one or more of a certain set of user tags to see a space, you can select this option and specify that set of user tags. If you have not yet added any user tags, you can directly do so by selecting 'Add/manage tags' from the drop down list.
Admins only. If you would like only admins to be able to view a space, simply choose 'Only users with any of these tags can see the space' and leave the set of tags empty (i.e. admins can always see all spaces).
Note that this is a per-space setting, so you can have some spaces that are visible to everyone, others that are visible to certain users, and others that are admin-only.
This setting is useful if you have resources and spaces that a user should not see, for example: a meeting room for staff only or a desk that can only be booked by certain users.
Finally, note that the ability to see a space doesn't necessarily mean that the user will have the ability to book it. The ability to create bookings is controlled by other settings like your Booking Conditions.