Majority government

A majority government is when a ruling party (or multiple ruling parties) has more than half the seats in a legislature. This is different from a minority government, when the party with the most seats in a legislature has less than half the seats, and a coalition government, when multiple different parties work together to govern. Usually when elections happen, the parties try to win a majority government. This is because majority governments let them pass all their legislation.
Sometimes, when parties have a very stable coalition for a very long time, people call it a majority government. One example of this is in Australia, where the Liberal and National have parties have worked together in a coalition for several decades.