To determine the sign of the product \(-16.8 \times \frac{3}{7}\), we can analyze the signs of both factors:
- \(-16.8\) is negative.
- \(\frac{3}{7}\) is positive (since both 3 and 7 are positive numbers).
When multiplying a negative number by a positive number, the result will be negative.
Therefore, the sign of the product \(-16.8 \times \frac{3}{7}\) is negative.