This is the 85th most frequent French word.
au
"Au" is the contraction of "à" (to, at) and "le" (the) in French, meaning "to the" or "at the."
Here, 'au' is used as a contraction of 'à le', indicating location. The noun 'bureau' is masculine singular, which determines the use of 'au'.
Il travaille au bureau.
He works at the office.
In this context, 'au' is a contraction of 'à le' and is used to express 'in the' with a masculine singular noun representing a season.
Au printemps, les fleurs fleurissent.
In spring, the flowers bloom.
In this sentence, 'au' is a contraction of 'à le', which means 'to the'. It is used because 'parc' is a masculine singular noun and requires the preposition 'à' to indicate movement towards it.