Discussions
The Discussions section in a course will show all open and closed discussions. Discussions pinned by instructors will show up at the top of the section.
The arrow (orange circle in the image above) allows you to collapse and expand discussion sections. The numbers in the orange box in the image above correspond to the number of unread replies and the number of replies respectively. For example, the graded discussion on "How has climate change affected you?" has 0 unread replies and 2 replies. The bookmark icon in the orange box allows you to subscribe to a discussion.
Opening a discussion lets you see the what others have been saying so far. You can then write a reply to the main topic, reply to other's replies, or like their reply. There are also options to search, filter, collapse, and expand replies (orange box in the image below).