German Translation
Wahre Freunde erkennt man in der Not.
This sentence is an example that uses the “impersonal se”.
This sentence has no subject (due to the use of the word “a” which is necessary because we’re talking about persons).
The “impersonal se” is not to be confused with the “passive voice se”, although they are very similar and often hard to be distinguished from each other.
Meaning, this sentence must not be translated as “True friends are identified …” (passive voice) because the Spanish sentence is not in the passive voice. It’s in third person singular. An appropriate translation would be “One identifies (or finds out who are) true friends …”.