Making a nested loop repeat before going back to main loop

and for the record "i" could be anything you choose to call it, its just the name of a local variable to the loop(and you can use it inside the loop as well)

I just use i as the variable name as shorthand for iteration, which of course means

Iteration means the act of repeating a process usually with the aim of approaching a desired goal or target or result.

unless I have a specific meaning for that variable

maybe this will help you see

void setup()
{
    Serial.begin(9600);
}

void loop()
{
    for(int counter = 0; counter < 10; counter++)
    {
        Serial.println(counter);
        delay(1000);
    }
}

which should count from 0-9 then reset and loop again (since its in the main loop)