if you @mention in teams the person, channel or team will receive a notification which they can click (depending on their alert settings) to go directly into the point in the conversation where they were mentioned.
To @ mention a person type @ and then their name in the conversation and select from the suggestions.
If you are in a meeting you can only @mention people.
To @ mention a channel type @channel and pick the channel from the list
To @mention a team type @team and pick the team