Pinmap for Arduino nano 33 BLE Sense

I have problem finding the right Port,Pin configuration for arduino-nano-33-ble-sense board.

I am using an open-source OS where I want to try a simple LED-ON example on specific pin. What I undestood from the following schemattic is somewhat confusing.

What does it mean GPIO25_A in the following schematic diagram(URL)? Does it mean PortA pin 25? But there is also P0.04 on that pin which would mean Port0 pin 4. I tried several pins from the schematic and it did not work as expected. I need more clerification. Also, I looked at nRF52840 datasheet for further reference. :tired_face: :tired_face:

https://content.arduino.cc/assets/NANO33BLE_V2.0_sch.pdf?_gl=1s219wr_gaMTM4ODA3MzA0NS4xNjM1NjA0MTMw_ga_SELSHHP7SG*MTYzNTgxOTUwMy4xNC4xLjE2MzU4MTk1MDMuMA..

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