This is the 1693rd most frequent Dutch word.
snelle
"Snelle" means "fast" or "quick" in English.
Here, 'snelle' is used as an attributive adjective describing the car ('auto') in the sentence.
De snelle auto rijdt door de straat.
The fast car drives through the street.
In this sentence, 'snelle' modifies the noun 'oplossing' (solution), showing that it was done quickly or promptly.
We hebben een snelle oplossing gevonden.
We found a quick solution.
Here, 'snelle' describes 'leerling' (learner), implying that he learns quickly or efficiently.