Is it P_IN jumper connectors or not?

Question

Electronics

As I understand it, these are jumpers to enable support for 3.3 V by the board and the initial state is off?

Answer 1

The circled jumper allows you to connect an external 3.3V source instead of using a roll.
The remaining two jumpers can be closed if the same unstable supply voltage is used instead of the external reference voltage for the ADC and other analog circuits as for the digital circuits.