Nationalism is a political ideology and movement that emphasizes the importance of a shared national identity, culture, and history among a group of people. It often leads to the promotion of the interests and aspirations of a particular nation. rephrase as a 9th grader shorten

Nationalism is a belief and action that says having a strong sense of belonging and pride in one's nation is really important. People who are nationalists often work towards making their country better and focus on their nation's culture, history, and identity.