This feature is available in the below setups:
Basic | Confident | Professional | Expert

Metadata are pieces of information (objects) that tie different sensor activations together. For monitoring tree health, a customer might assign the information about the type of tree, let's say "oak" to 5 different sensor activations. Now the customer can click on the metadata object "oak" and will see all sensors with activations that have the object "oak" assigned to it. 

Metadata is assigned to a sensor via activation. Find out how to activate a sensor in this article.