When you block a number on an iPhone, what will show up when that person texts you?

I gave someone my number and I want to block them because I don't know them very well. However, I don't want to seem mean, so what will happen when that person texts me? Will it say, "Number not available" or will it send but I just won't receive it?

Nothing it "goes through the system" but it doesn't go into your phone

You won't be able to see the message if you blocked that person.

You don't get the message so nothing