On the right, you can see the interface that appears when you select the action Identify Language.
There are two elements in the interface: Type and Detection threshold.
Depending on the value selected, an additional field will appear to include either the text or the URL to analyze.
The output is made of two fields: languages and language_names. The former returns a list of the languages detected separated by commas using the codes defined by the ISO639-1 standard; the latter returns that same list but using the languages names instead of the code.
In the next image, you can see the results of testing the app in Zapier: