Is it necessary for people to play against computers for computers to be able to learn without further coding?
No, playing against oneself and playing against others would be more or less equal, although neural nets are usually "jumpstarted" by training it with large sets of standard tactical and positional ideas that may come from human games
Is there any part of computers that has any understanding of words that are typed?
This is very anthropocentric, when IBM's Watson won Jeopardy!
Even if it does not have self awareness, it surely has a great deal of functional knowledge.
Your intuition is "humans understand, a computer is not human because it works in a different way, therefore a computer does not understand".
The truth in it is that a computer program typical lacks layers of functionality we have. It has no layer of self awareness. It has no levels for analysing its own function. However such things are possible.
Deep learning can lead to deep abstraction: nodes that correspond to subtle notions far removed from the inputs. This is much how human brains work.
My girlfriend has an Ipad and she is very happy with it.