This is the 9672nd most frequent Spanish word.
aseguren
"Ensure" or "secure" (third-person plural subjunctive or imperative form of "asegurar").
Here, 'aseguren' is a formal imperative directed towards a group, instructing them to ensure something.
Aseguren los documentos importantes en un lugar seguro.
Ensure the important documents are in a safe place.
In this case, 'aseguren' is in present subjunctive mood, used in an expression of necessity or importance.
Es importante que ellos aseguren la calidad de los productos.
It's important that they ensure the quality of the products.
'Aseguren' here is again a formal imperative directed at a group, requesting them to ensure a condition.