This is the 3rd most frequent Catalan word.
a
The Catalan word "a" means "to" or "at" in English.
In this sentence, 'a' indicates the time when an action occurs, similar to 'at' in English.
L'estudi he de llegir-lo a la nit.
The study must be read at night.
Here, 'a' is used in the context of location, translating as 'at' or 'beside' in English to specify proximity.
La casa era a la vora del riu.
The house was beside the river.
In this sentence, 'a' signifies movement toward a location, equivalent to 'to' in English.