This is the 279th most frequent Swedish word.
nilsson
"Nilsson" is a Swedish surname and does not have a specific standalone meaning in English.
Here, 'Nilsson' is used as a surname, referring to a person respectfully.
Fru Nilsson är min lärare.
Mrs. Nilsson is my teacher.
'Nilsson' here is used with a possessive suffix, indicating ownership of the book.
Nilssons bok ligger på bordet.
Nilsson's book is on the table.
In this context, 'Nilssons' refers to a family with the surname Nilsson, in plural form.