The answer.
Nine parameters: carbon dioxide, particulate matter, air pressure, humidity, formaldehyde, temperature, nitrogen dioxide, volatile organic compounds and carbon monoxide. Final specifications and performance details will be confirmed before launch.
A little more context.
Different readings describe different aspects of the indoor environment. Temperature and humidity describe conditions in a room, while particle and gas measurements provide other parts of the picture.
The list describes the product in development. Before buying, check the final specifications and published performance information to understand what the finished device measures and how those readings should be interpreted.