The degree of a polynomial is the highest exponent of its variables. In the case of the polynomial -7xy^3z^2, the degree is the highest exponent among x, y, and z.
The highest exponent is 3, which is the exponent of y. So the degree of the polynomial -7xy^3z^2 is 3.
It's worth noting that the coefficient -7 has no effect on the degree of the polynomial. The degree of a polynomial is determined by the exponents of its variables, not its coefficients.