Salem

I always wondering what will be if i click "Reset" button

in what context ?

ctrl+T, so skills window, there is "Reset" button

A long time ago in a Salem since forgotten, studying the same item caused a debuff to your study progress. If you studied inefficiently you could actually back yourself in to a corner and not be able to gain any profs. So the "reset" button removed all your progress and reset the debuff so you weren't stuck. The present debuff is much less penalizing (excess use of inspiration)

You loose all current progress in all progression (inspirationals) bars. But also resets inspirationals (ie. if you used 10 dried roses, and found out that the cost was/is too high, that resets as well)

** But ofcourse doesn't give you back the already used inspiration...

**** Salem does not allow nice things.

indeed: once upon a time studying used to give reduced proficiency points with each duplicate item that you studied.
So it was very possible to get a 0.001 multiplier by studying hundreds of woodchoppings, effectively making it impossible to get another proficiency up -- this reset button is a nice thing

Of course, as stated higher, the current duplicate penalty is much less bad.