。
Defensive driving prevents accidents.
Literal
Preventive-driving [topic-は] accident [object-を] prevent-[polite-ます].
予防運転 ('preventive/defensive driving') is a straightforward compound. The main teaching point is the topic–comment shape: 予防運転は sets up the topic, and the rest comments on what it does. 防ぐ ('to prevent, guard against') takes a direct object with を and is common in safety and health register.