I had to google 'kantele'. But my wife informs me that it's featured in the 19th century Finnish epic 'Kalevala'.
What is a kantele?
It is the traditional stringed instrument of Finland-- a lap harp essentially.
This website provides a neat dissertation about the kantele, written by Carl Rahkonen.
And here is a performance of the kantele by Einherjer.
Kiitos !! :>
How to say this is the kantele?
I'd say "tämä on se kantele", which translates to "this is that kantele".
"Tämä on kantele", although it could technically be "this is the kantele", just doesn't sound like it, so I would't translate it as such.
Thanks for the explanation.
Thanks to the Finnish language fathers too, to make our life impossible