permutation of nothing

Question

$p(n,k)$

$k=0$

$p(n,k)=n!/n!=1$

what 1 means? when There is no choice why there will be 1 situation?

Answer 1

Well, $1$ means that there is one choice. And, yes, there is exactly one choice. That is, if a set $S$ has $n$ elements, then it has exactly one subset with $n$ elements, which is $S$ itself.

Answer 2

How many ways can you choose $0$ objects from a set of $n$

$1$ way (i.e none are chosen)