How to limit access to a content to particular users only?

1. Using Roles & Access Control, create a custom role.
2. Go to Manage content.
3. Go to a content which you want to be viewed by users with this custom role only, and set this content to custom roles. Save.
4. Return to Roles & Access Control, and choose this content to make it accessible for this custom role.

Now, simply assign this newly created custom role to users to whom you want to make it accessible.