How is it going meaning?

"How is it going?" is just a friendly hello. It means the same as "How are you?". Here in Australia, we say it all the time. It is very casual. You can say it to your mates. Or to the person at the coffee shop.

The 'it' just means your life or your day. They are asking if you are okay. You do not need to give a long answer. A short reply is normal. You can say, "Good, thanks. How about you?". Or just "Not bad". Sometimes I just say "Yeah, good". It is more of a greeting. It is not a real question about your whole life. So a simple answer is perfect. Hope this helps.