It is most likely a pitot tube speedometer. There should be a plastic finger hanging off the transom that extends just below the bottom of the boat. Check this for damage as well as the little hose that is connected to it. They are designed to fold back in the event of striking a submerged object and can be snapped back in place.
This link is what the tube looks like that I am referencing:
https://www.amazon.com/Pitot-Tube-Marine-Speedometer-56973P/dp/B00YMT398U&ved=2ahUKEwjsmoaW_v3mAhXOo1kKHZ-vCTsQFjAEegQIAhAB&usg=AOvVaw0s7Flec8PdaKswdXeXtZ_Z
