This is the 902nd most frequent Catalan word.
comencen
"Comencen" means "they start" or "they begin" in English.
Here, 'comencen' expresses the initiation of an action, in this case, the flowering of plants.
Quan comencen les flors a florir, és senyal de la primavera.
When the flowers start blooming, it's a sign of spring.
In this example, 'comencen' is used to describe the sequence of events starting at the speech for the party.
Els esdeveniments de la festa comencen amb un discurs.
The events of the party begin with a speech.
In this sentence, 'comencen' functions as a verb in the present tense, third person plural, indicating the start or beginning of classes.