Direct Action goes beyond just holding banners and shouting slogans - which is certainly a good thing to do as well! - it is any action which aims to physically block, or make more difficult, environmental destruction. It may not always ultimately stop the road being built or whatever, but what it does do is impose extra economic costs on "developers", making destructive "development" more expensive. The vast majority of green direct action is Non-Violent Direct Action (NVDA).