What do you need to know to understand what is here (in the picture)?

Question

Electronics

Answer 1

Everything is written there. Modular electroencephalograph (EEG). The top picture shows an isolated microcontroller module with an analog-to-digital converter. The bottom picture shows a 2-channel EEG amplification module.
In order to learn this, it is enough to know English.
If you read the datasheets for the microcircuits used (signed rectangles with more than two contacts) or just from the experience of drawing / reading circuits, it is clear that in the first picture on the left there is a microcontroller with its harness, on the top right is the power supply, on the bottom right is the RS interface -232.
In the second picture (we read the captions) there are two channels for processing the measured signals, which consist of (from left to right): protection against static current limiting, an amplifier with a constant gain of 12.2, an amplifier with a variable gain with G=6...100 , a 3rd order Bessel filter with a frequency of Fc = 59Hz (I suspect that it is needed here to cut off network interference).
Below in the second picture is another channel .... calibration.
The easiest way to read the diagram is to go from the problem, select large blocks, and then more and more detailed to the required level.

Answer 2

It is elementary to be able to read.

Answer 3

Electronics, circuitry and English.
To get a more specific answer, you need to ask a more specific question.