This is the 11604th most frequent French word.
réservent
"Réservent" means "reserve" or "keep" (third person plural form).
Here, the word 'réservent' is used as a verb in the present tense, meaning 'they reserve'.
Ils réservent une table pour le dîner.
They reserve a table for dinner.
In this sentence, 'réservés' serves as a past participle used as an adjective, meaning 'reserved' and describing 'spaces'.
Les espaces réservés aux clients doivent rester libres.
The spaces reserved for clients must remain free.
Here, 'se réservent' is used as a pronominal verb, meaning 'they save for themselves'.