This is a Tic Tac Toe game as everyone knows it with a bit of customisation. You can set your own number of symbols in 1 line that a player needs to win (win combo) and you can also play against more than 1 player, which can be either another person or a computer.
The bottom bar shows the current state of the game. It tells you who is playing, who has won, who should confirm their turn, etc. You can place your glyph on the board by simply tapping or clicking on the cell you have chosen. By default, touch screens require you to confirm your moves, but you can change this behaviour in the settings. This is to avoid missed moves where you accidentally tap the wrong cell, which can lead to frustrating experience.
As you may have noticed, there are many ways to customise your experience. There's a brief description under each option. Except for the grid sizes, any changes you make to the configuration will be applied to the game immediately, but I can't guarantee how well they will be applied to the game, so it's always a good idea to restart the game if you make major changes to the configuration. Although you can set custom values, some values outside the slider range may not be supported. Negative values are generally not supported.