“Frog” (rana) you may know. You may have eaten “frogs legs” (ancas de rana) on a trip to France.
So, is there a frog in your throat? This is an idiom which means that a person has trouble speaking due to a dry throat or hoarseness (ronquera). Perhaps in Spanish you would say that someone “tiene carraspera”.
Why “frog”? Because the sound is similar to the croaking sound (sonido de croar) that frogs make.