Can anyone explain me this code? what is this void and this is static?

Question

#include <stdio.h>

void say_hello();

int main() {
int i;

for (i = 0; i < 5; i++) {
say_hello();
}

return 0;
}

void say_hello() {
static int num_calls = 1;

printf("Hello number %d\n", num_calls);
num_calls++;

}

Answer 1

void just means, that a function of method has no return value. static is the modifier to make a class, method or variable static, which means it only exists once per run (in easy words).

Answer 2

void means , function never returns any value to called function.
static is a storage class .
scope of the static variable is specified to the block it is defined .
life span is till the program ends.that means value of static variable is persists between the functions