This is the 15270th most frequent German word.
unerklärliche
"Inexplicable" or "unexplainable."
Here, 'unerklärliche' is an adjective describing 'Situation', indicating something that cannot be easily explained.
Die unerklärliche Situation verwirrte alle.
The inexplicable situation confused everyone.
In this example, 'unerklärlichen' is attributively modifying 'Phänomen', describing it as being beyond explanation.
Der Wissenschaftler stand vor einem unerklärlichen Phänomen.
The scientist was faced with an inexplicable phenomenon.
Here, 'unerklärliche' describes 'Freude', identifying the nature of the joy as not having a clear reason.