Thanks you have been very helpful !
Hi there and welcome. Well, you can think of it as how quickly you fill a tampon or pad. If you are changing every hour, you are heavy. Every couple to four, you are moderate and needing to (although you still may for freshness) less than that is light.
Periods usually have a flow to them that is pretty routine. Starts out light and then gets heavy. Heavy for a day or so and then moderate for a day or so and then back to light. That is probably a pretty normal pattern although each woman will have variations of that. good luck (I sometimes skip the light to start off with and immediately have a heavy flow).