An assignee is a person (or persons) assigned to a task. You can show who is assigned to a task by adjusting your default task view and dartboard settings.

You can hide/show assignees beside tasks by adjusting the default view from the layout dropdown menu:

You can also hover over an assignee on your dartboard to add/remove assignees:

You can hide/show the assignees of individual tasks. To make the assignee visible by default on all tasks, go to the Settings section from the left-hand column. Then choose Properties > Assignees

Toggle on "Show" to show the assignee by default. If you want to show multiple users, also toggle on "multiple users."

Assignees, when visible, will appear under and to the right of the main task title. Assignees will also show beside any subtasks (if applicable) within the task:

If you want to hide the property in the future, or adjust other assignee properties, you can hover over the assignee section on any task and choose to hide the assignee property or return to the property settings to adjust your settings:

You can also hover over an assignee in a task to add and/or remove assignees: