What is the Default Pawn class and what is used for?

I’m newbie in Unreal Engine and also in games development.

I have developed my own version of Pong game (sources here) and I’m confuse with the behaviour of DefaultPawnClass: Its creating another Paddle in game (I posted a question about it here).

I have to questions:

What is Default Pawn class?

And, what is it used for?

Its the Pawn that get automaticly Spawned when you start the Game and gets Possesed by the Default Controller. In your case you create 2 Paddles from GameMode but you already get 1 Spawned by default for the Player.