The simple straightforward meaning of dreaming of killing snakes is that soon you will realize whom to trust and who not to trust. There will be some important incident in your life and at that time you will realize who your true friends are.
Dreaming of killing black snake in dream means that you will be able to overcome a tough situation in life soon.
Dreaming of killing cobra means you will have victory over your enemies and competitors.
Dreaming of killing yellow snakes means you will face pressure from family to give up on your dream.
Dreaming of killing of green snakes means you won’t be happy with a new decision.