Price Action deals with studying how the prices moved earlier and making actionable deductions. It is somewhat analogous to how an art collector evaluates a painting: judging the brush strokes, seeing the color combination, and seeing some symbolic meaning, etc.
A proficient trader is nothing but an art collector (who collects money!) following the analogy. She judges what the dominant trend is, senses the mood, and gauges what story the charts tell her. You will be able to decipher all this information by studying the Price Action.
The main goal for a retail trader is to judge the buying/selling pressure accurately. When there are more buyers than sellers, it results in buying pressure. More buyers than sellers, more buying pressure. The same case with the selling pressure, more sellers = more selling pressure.
So when I say patterns repeat, what I mean is: Buyer/seller imbalances keep on occurring.
Yes, the markets are random, but the above discussion brings us closer to the notion that there are few moments where price movement is less random than usual- and we are here to hunt for them. The upcoming chapters discuss the catalog of scenarios that pose to be less-random than usual.
If we extend the above discussion further, we find that market structure( price moving consistently in a particular way) has to change in finite ways.
Again, I endorse that the markets are random, but it can take one of the foreseeable directions. Move up, down, or stay flat. Price will not jump from 1 to 1000 to 30 to 50 in an instant. Sometimes it will change directions and give you clues because it follows what we can call the “Price Etiquettes”.
A good grasp of Price Action makes you trade in the right direction more often than not.