"Close friends" is an option that allows you to bookmark your favorite friends and add them to the Close list. How to do it?
Log in to your account, click on the green icon where you usually see your friends. Find the selected friend and click on the image of a player with a star on it.
This way you can monitor the activity of the selected players, even when you are not in the game. You will receive a notification on your mobile device every time one of your close friends enters BelotBG and you are not online.