A property is an attribute of a resource or of a component, and is the place where data is stored in Measure Mode. Step 1 of the public process "Riffyn: Fermentation" has different Properties assigned to each Resource Type and Component.
Fixed Properties are indicated by the Tag icon to the left of the Property name (More information about Fixed and Non-fixed Properties).
Properties are placeholders for data (manually entered, or uploaded from a file), but also a place to record the specifications for how you expect your process to behave. You can list target values and specification limits for each Property when in Design Mode. When executing an experiment, target values will be available for reference and all target/specification values will be listed in the exported data table.
Properties and Components should be used together instead of using specific Property names. A Property "Nitrogen Source Type" could alternatively be represented as a property called "Type" within a Component called as "Nitrogen Source".