When Grouped View is selected, all conversations with the same person or group of people are grouped together in the list with a header showing the person's or group's name. The list is still sorted chronologically, and the groups with the most recent messages are at the top. To see individual conversations and messages, expand the group and select the desired conversation. When you receive a new message, the group heading is bolded and marked with a red dot, similar to how conversations with new messages are marked. In the screenshot, Premal sent me a message, so the group heading and the conversation with the message are both marked as having new messages.