zero only part of an array, rather than the whole thing

[Will 保哥]

This sentence zero only part of an array, rather than the whole thing is really hard to understand for me. Can you describe more or change another way to say it?

I know what "pay only for what you use, not what you could have used" mean. Just don't get it what the "zero" means. It's a verb or noun?

[Scott Leggett]

In this context, "zero" is a verb taking the second definition here.

(transitive, computing) To change a memory location or range to values of zero; to set a variable in a computer program to zero.