It is possible to make parts or an entire module visible/hidden to students. When a part or an entire module is hidden, you will see this indicated by an eye with a line through it. In the example below, the Course Planning and Contact Information are hidden, but the rest are visible. You can adjust this by clicking on the toggle at the top where it currently says Hidden (it will say Visible when it is visible).

Additionally, there is the option to apply Release Conditions. You can read more about this under How do I use release conditions?