It was a light touch - they never shut down, they still don't wear masks. At first it looked bad, they had a higher rate of infection and death than other Scandinavian countries, but then it dropped away. So far it is still low. Much lower than western Europe/US, and those countries locked down.

Some people have interpreted this as herd immunity, but very hard to say this, and it does look like cases may be rising again.

This link explains well:
Sweden's gamble | Science