In sports like football or soccer, the kickoff is the kick that starts the game, or starts play again after a goal is scored. Outside of sports, English speakers borrow the word to talk about the start of ANY event — a meeting, a project, a sale. You'll often see 'kickoff meeting' at work, meaning the first meeting where a new project officially begins. It's a fairly informal, energetic word — it makes the start sound exciting, not just administrative.

（足球等）開球；（活動、專案的）開始、開幕，常見於「啟動會議」等職場用語。