You have two main options for communicating with students in Canvas.

Announcements

Use Announcements to make announcements to all users (both students and staff) and to specific sections. Canvas sends students an email notification when an announcement is made, according to their set notification preferences.

Conversations/Inbox

Use Conversations/ Inbox to communicate with a course, a group, an individual student, or a group of students, and to view and reply to conversations and sort them by course or inbox type.

Read more on Canvas Community: