This is the 6528th most frequent Swedish word.
mathias
"Mathias" is a masculine given name in Swedish, equivalent to "Matthias" or "Matthew" in English.
In this sentence, 'Mathias' is used as a proper noun, specifically a person's name.
Mathias är min vän.
Mathias is my friend.
Here, 'Mathias' again acts as a proper noun, denoting the same individual referenced.
Jag såg Mathias på restaurangen igår.
I saw Mathias at the restaurant yesterday.
In this case, 'Mathias' remains a proper noun referring to the individual as the subject of a story.