It has headers and through-holes so you can either solder wires or components directly to it, or use the headers already soldered in place.
Connect VCCA to 5V and VCCB to 3.3V (or the other way round if you prefer).
Connect GND on the level shifter to GND on your circuit (both microcontroller and the rest of the circuit should all have a common GND)
Then connect up ports on your 3.3V device (e.g. Pi or Wemos) to B0-B7
Connect ports on your 5V device (e.g. sensor or Arduino) to A0-A7
This should enable your 3V3 and 5V devices to safely 'talk' to each other with no risk of damaging ports.