Is this a 3.3V to 5V logic level converter?
The page says 'I've used Zener diodes(3V6) and 150 ohms current limiting resistor so as to clamp the 5V high level to 3.6 volts as per specs.', and this is indeed what they'll do. So it'll be OK to connect this to a Uno with 5V I/O.

It's odd that the page describes it as an 'SPI' interface, because it's certainly not SPI, it looks more like I2C. The SIO line is bidirectional (i.e. at some times the sensor drives it and the Arduino receives the data), and this means the OM10B will be driving 3.3V into the Uno's 5V logic input. This isn't going to damage anything, but 3.3V is right on the edge of what counts as a '1' for most 5V logic. You may find that, if there's lots of noise (e.g. long wires or poor grounding) the data starts getting corrupted.

If that happens, you can use a 3V3-to-5V bidirectional logic level converter circuit instead of the resistors and Zeners. Adafruit &amp; others sell them, or google 'MOSFET level shifter' for circuits.