Conga Grid utilizes the Salesforce Chatter product to communicate with other members of their org. Conga Grid users can request actions be taken on specific fields in a grid and see that request in Chatter. Responsible parties receive a notification of the request and can see notification indicators on fields in their grid. The @mention tag is used to notify a specific person using Chatter. The @mentioned party sees the message in Chatter and is able to respond accordingly.

All activities, @mentions, and requests can be seen in Chatter; Salesforce's instant messaging product. For more information on Salesforce Chatter, see https://www.salesforce.com/products/chatter/overview/

If you want to request actions on fields in a grid, see Request Actions.