I need help to understand "For each" and "Fetch Record"

I need help to understand "For each" and "Fetch Record"

I am following this tutorial:

       https://www.zoho.com/creator/help/tutorials/add-advanced-scripting.html#enhancements

and I am stuck with this excercise:

//Set Total value with 0.0 USD
input.Total = 0.0;
//loop through all the selected Items and calculate total
//"For each list" task is used
for each itemID in input.Products
{
//Get the Product Row from the Products form
//Fetch record task
productRow = Products [ID == itemID];
//Calculate Total Price
input.Total = (input.Total + productRow.Price);
}


what is itemID and productRow?

Should I define this as my variable?