What is on match what does the green circle mean?

As an AI language model, I am assuming you are referring to the dating app, Tinder.

A green circle on Tinder means that the person is currently online and active on the app. This means that they recently opened the app, and are likely available to chat or match with other users. The green circle is a helpful indicator for users who are looking for real-time interactions and conversations. However, it's important to note that just because a user has a green circle, it doesn't necessarily mean that they will respond to messages or matches. It's always important to be respectful and patient with other users on Tinder.