Whether you're building a weather station because you don't trust your TV forecaster, or a system to keep your exotic lizard comfortable, HTU21D click gives you an easy way to add a humidity and temperature sensor to your design.
These days when we print a silkscreen cloud onto a PCB it's usually to show that it has something to do with IoT. Not with HTU21D click. This one carries a high-precision, fully calibrated humidity and temperature sensor so it's an old-fashioned water vapor cloud.
Which isn't to say you can't turn it into a smart thing. You could connect it to a mikroBUS™ on, say, clicker 2 (HTU21D uses I2c lines and a 3.3V power supply). Then put a WiFi click next to it, and feed humidity and temperature data to a… cloud.
Just keep this in mind while you're developing:
Relative humidity is dependent on temperature, so make sure to place HTU21D click somewhere where it can get correct temperature readings of the environment. That is to say, don't place it right next to the heater in your terrarium, or next to a hot metal railing on your porch.
If you can follow that, then you'll get reliable humidity and temp. data. The measurement range is from 0 to 100 percent for relative humidity. For temperature, the sensor's specified range is from -40 to +125 degrees Celsius (your hypothetical lizard wouldn't survive neither of those by the way).