What is the Simply 21 - Blackjack game, how does it work?

According to the introduction of ExtraAndroary, Simply 21 - Blackjack is a Card game on the Android platform. There is currently a 1.5.8 version released on Mar 20, 2020, you can see the details below.

Simple card game. Place the poker cards on 4 stacks - each stack must have a value of 21 (similar to Black Jack).

Jack, Queen, King: 10 points.
Ace: 1 or 11 points.

This game is powered by libgdx.