Not sure about your specific example, but yes slavery was practiced in Sweden. Thralldom was actually quite important to the Norse economy. During the Viking Age captured people could be taken as thralls, although you could also wind up as someones property due to debt. A thrall did not have rights like a freeman and would be bound to serve a master, unless that master eventually freed them (in which case they still owed him certain duties).

Persian traveler Ibn Rustah claimed they took Slavic slaves from the near the Volga. These slaves could be traded or taken back with them for labour. There is plenty of evidence that at times they enslaved those they raided in Britain.

Eventually, Sweden outlawed thralldom for those born to Christian parents in 14th Century.

It should be noted that thralldom was not the same as serfdom as a non-slave serf was afforded certain legal rights and protections. Of course they were by no means equal or entirely free, I have read court cases were serfs were forced to return to cruel masters they escaped from, but the fact that they were able to legally represent themselves highlights the difference between a serf and a slave. A slave was legal property, but you typically could not sell your serf like they were a slave even though they were still legally bound to you.

NOTE- I did some quick research and it seems other people have made mention of slave raiding in Finland for blonde slaves. However, I am unfamiliar with this and did not see any sources. It sounds like it could very well be true, but I would advise doing some research into it if you are interested. Hopefully someone might comment with more information.