@pytest.fixture is used in pytest tests to prepare a certain operation or data in advance and clean it after the test. So, instead of repeating the same preparations every time you need to do each test, you can write this once and tell pytest to "prepare this at the beginning of each test."

To understand better, you can watch this 1 minute long video. https://www.youtube.com/watch?v=1of-iRbwgr0