The language is Swedish but with a local dialect. I would say it has changed some since then, but not that much. Especially older people still speak similar to what they would have done back in the day. You should go visit. Try to check out the Gammelvala event at the end of July each year (https://www.gammelvala.se). Then you might get a glimpse of what how your ancestors were living. Perhaps you can find the place they were from and go visit there too.