This is the 6242nd most frequent Spanish word.
aseguran
"They assure" or "they secure."
In this sentence, 'aseguran' attributes certainty to experts regarding their statement about climate change.
Los expertos aseguran que el clima está cambiando rápidamente.
Experts assure that the climate is changing rapidly.
'Aseguran' is used here to mean checking or securing something to ensure it is safe or proper.
Antes de salir, aseguran todas las puertas y ventanas.
Before leaving, they ensure all the doors and windows are secured.
'Aseguran' signifies giving assurance or commitment about future actions.