This is the 3221st most frequent Swedish word.
sean
"Sean" is not a Swedish word; it is typically a name. If you meant "sedan," it means "since" or "then" in English.
In this sentence, 'Sean' is used as a proper name and serves as the subject of the sentence.
Sean går till skolan varje morgon.
Sean goes to school every morning.
Here, 'sen' (pronounced similarly to 'sen', the English 'sean' transliteration) is an adjective describing the lateness of a time period, distinct from 'Sean' the name.
Efter filmen var det en sen stund innan vi gick hem.
After the movie, it was a late moment before we went home.
In this case, 'Sean' remains a proper noun, referring to the person's name, 'Sean', encountered within the sentence.