The Beguines were a religious movement of widows and single women which began in the "Low Countries" in about the 12th Century. By "Low Countries" I mean something broader than the Netherlands - we're also talking about mdoern-day Belgium, parts of Northern France, Western Germany and probably Luxembourg too.
Originally it was a lifestyle whereby the woman (there were some men, but the vast majority were women) could live a religious, "consecrated" life whilst in her own home. Later they congregated and lived together in "Begijenhoven" - in houses grouped around a church. They also began to wear habits and the in pictures I've seen of them I've seen little to distinguish them from any order who wore a full habit.
What really made them distinctive was that they took no vows. I once read a quote that said something like "The Beguine faithfully re-dedicates herself every day, since she has taken no vows for the rest of her life." Each Beguine lived in the Begijnhof of her own free will and was able to leave at any time she wished. There was little or no organisation or structure to the movement, which seemed to simply spread from town to town.
I
think - I haven't read about this in a while - that it took a while (= probably a couple of centuries

) for Church authorities to accept and come to terms with this form of "religious life". The movement gradually died out after the turmoils of country border re-drawing and the Reformation. As I said, I believe the last Beguine in Amsterdam lived until 1986.
The Begijnhoven themselves are popular tourist attractions now, being as they often are places of stillness in the centre of busy cities.
Unfortunately I know little of their spirituality (and I have to run to Mass now so I can't do some looking up and/or translating for you!). I hope that this helps a little nevertheless.
Love and prayers,
PP