Patriotism: This term refers to love for one's country and willingness to sacrifice for it. It's similar to how you might feel about your family - ready to support them no matter what.
Nation-State: A state whose citizens are relatively homogeneous in factors such as language or common descent. Like everyone in a club sharing the same hobby or interest.
Sovereignty: The authority of a state to govern itself. It's like being the captain of your own ship, deciding where to sail and how to navigate.