Every home should have one

But what is it?!

This was proudly offered for sale in the local hardware shop (probably still is). I asked the lads who work there for an explanation of the apparently oxymoronic name of this odd (and expensive) device. What does it do?
They clearly hadn't a clue, but obligingly explained, in words of one syllable (because girls don't understand about tools - notwithstanding that the Boss is a girl and certainly does!), what a planer is. Well duh... But 'thicknesser'? Is that even a word?

Can any clever-pants out there enlighten?