The raise hand feature available now in Microsoft Teams that allows the participant to notify the host and others that he have something to share in the conversation. This feature is quite useful for companies that hold webinars with multiple participants.

Click on the raise hand feature in the meeting:

When a meeting participant has raised their hand, an icon will appear next to their name in the roster view as well as their profile picture or video on the main meeting stage. 

Both the attendee who raised their hand and any presenter can lower individual hands in the meeting. 

Click again the raise hand feature to lower down your hand: