In this section you can have an overview of what are the news, messages, and updates. The following screenshot shows the Office Message center:

When you click on a message that has Act by column information, it is important that you read it and plan your actions, as shown in the following screenshot:

When you click on the Additional information link, you will be redirected to a support article that describes the change, at https://support.microsoft.com/en-us/help/4057306/preparing-for-tls-1-2-in-office-365.

You can also edit your preferences in the Edit Message center preferences section and receive emails notifying you of the changes.