I presume your meter is exposed and not in a ground box. The wire and clamps complete the grounding circuit to earth ground through your home’s water line when it goes into the outside soil. Plastic water meters and/or dialectric meter unions will break that grounding circuit leaving your house with not grounding protection.
If the clamps can not be easily cleaned with a steel brush, replaced them with new clamps and wire if also corroded.
1. Be very careful when removing clamps and wire. There may be minimal voltage and possible spark.
2. Clean piping too a shine before installing new clamps. A good connection is very important at these two points.
3. Install wire jumper. Make sure screws clamping wire is very tight.
4. Recheck clamp screws.
5. Paint the clamps with good coat of paint to protect them from the surrounding air and possible vapors.
I ran into the lack of a “grounding loop” around water meters while dealing with premature anode/water heater tank failures. If this interests anyone I can explain more.