You can directly assign the selected record to the User/Team.
As you click on that icon, the Assign to User or Team popup window will open to select the User/Team. 
After selecting User/Teams, click on the Assign button. 
You can add the Task of selected records by clicking on Add Task icon. 
As you click on that icon, the Add Task popup window will open to insert the Task-related details. 
After clicking on Create button, Task will be added. 
Similarly, you can add the ‘Appointment’ of selected records by selecting the Appointment activity from the drop-down action.