Zero at Work

In $7x^{0}$, the exponent 0 applies only to the $x$. For nonzero $x$, $x^{0} = 1$, so $7x^{0} = 7\cdot 1 = 7$.

With parentheses, the whole product is the base. For nonzero $x$, $\left(7x\right)^{0} = 1$, because the exponent now applies to $7x$ as a whole. The example shows that the parentheses decide what the exponent applies to.

A zero exponent turns its base into the factor 1. The rest of the expression stays as it is. So $7x^{0}$ keeps the 7 and loses only the $x$.