凡事 means 'everything' or 'all matters', but it is used for general statements or rules rather than concrete objects. It often appears at the start of a sentence or clause to introduce a universal principle or condition. Unlike 一切 (yīqiè, 'all things'), 凡事 is more abstract and pairs naturally with 都 (dōu) to mean 'in every case' or 'every matter'.