The four pins

What is on the board

A 12 mm square push switch, two small resistors at the right-hand edge, a red LED under the switch, and a four-pin header along the bottom. The header is right-angled, so the pins point out past the edge of the board and the block lies flat in a breadboard or on a cable.

The four names

GND is the return path, on the square pad. Both resistors on the board end here.

VCC goes to one side of the switch and to nothing else on the board. The net list, which is the list of every electrical connection on the board, has exactly two entries for it: this pin and the switch.

NC means not connected, and here it means it literally. The net list does not mention it at all.

SIGNAL is the other side of the switch. A 10 kΩ resistor ties it to GND, and the red LED hangs off it too. Switch off, it reads LOW. Switch on, the switch connects it to VCC and it reads HIGH, and the LED lights. That is what ACTIVE HIGH on the front means.

VCC is the one to choose

On the XL LED you could leave the supply out, because there was none. Here VCC matters twice. It is the only thing that can make SIGNAL HIGH, so without it the block always reads LOW. And when the switch is on, SIGNAL is VCC, so the voltage you feed it is the voltage your board's input pin sees.

That makes the rule simple: VCC goes to your board's own logic supply. 3V3 beside an ESP32, an ESP32-S3 or a Pico. 5V on an Uno. Which supply to use shows what happens with the other choice.

The back of the board

Turned over, the order reverses. The square pad is on the right, and it is still GND. The back is where the part number is printed, TK05, and the two lines under the header are the whole instruction manual for the switch.