There are number of functions that enable a host/moderator to manage the flow and interaction-level of meeting participants.

The moderator has the power to mute others, disable their video, or even remove them from the chat room.

Furthermore, in the text-chat section, there is a tab for polls to be created.

The host has also the ability to set a password for more security of undesired participants - as well as a lobby, where people have to enter a username first.

Here are some more articles to get you started with Jitsi:

Jitsi Meet (main article)

How to create a meeting

Jitsi Features - Audio & Video settings, Text chat, Screen sharing and Video sharing

How to invite friends to your meeting