The majority of commentators from time believe that the Lord's words here to be figurative. They certainly had power to heal the sick and to cast out demons, but this language is very excessive and because it's intended to be understood in a figurative way.
You may have great enemies in the office, and yet in God's good time souls may be won and saved. You will in a sense have victory over the snakes and over the scorpions with their vicious stings. There will be tremendous hostility, even venom and opposition, but your work will triumph in the end. That is the promise of the Lord.