this was an exciting stamp to receive! even the priority mail sticker is in a hexagonal shape. it is part of a series of six stamps of Changes in Everyday Finland issued in October 2014. I actually got two postcards from Finland on the same day with a different one of these stamps on each (so, if I was excited about one, you can imagine my excitement at getting two, at the same time!) - but for the life of me I now can't find the other one...
they are non-denominational first class stamps and the designs "depict six megatrends that have changed everyday life: information technology, culinary culture, domestic appliances, migration, pop culture and vehicles."
below is a picture of the set I found from linns.com, and here is a link to the artist Sami Saramäki's work. there will be more in this series coming in the next couple of years leading up to the Finland's celebration of it's 100th year of independence in 2017.