Understanding a question about gradient on corresponding level sets

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I am having difficulty understanding what this question is asking for, and was wondering if someone could shed some light on it.

$f: \mathbb R^{m} \rightarrow \mathbb R$ is defined by

$f(x, y, z)=z^{2} - x^{2} - y^{2}$

Define the level set of $f$ for the value c to be

$\sum_{c} := \{x \in \mathbb R : f(x) = c \}$

Compute $\nabla f$. Indicate $\nabla f$ as a vector at the points $(1,0,0), (0,1,0),(0,0,1)$ on the corresponding level sets.

I know that $\nabla f(x,y,z) = (-2x, -2y, 2z)$. Is the question asking for the value of $\nabla f$ at the points $(1,0,0), (0,1,0),(0,0,1)$ or does it want to be expressed in terms of these points, or something else entirely?