Can it be a fine for overexpenditure of smth?

It means nothing. Where did you read it?

I'm not quite sure if 'overrunnings' (i.e. with "s") does exist... anyway, I'm just thinking of 'overrunning' as "exceeding the alloted budget or limit (or time)", and that the sentence implies an imposing of interest rate for exceeding the budget. a typical example is, if you happen to overrun the credit limit of your credit card for instance, there would be an appropriate interest rate that will be applied for the amount exceeding the given credit limit. say, the interest rate is 2% per annum for the credit limit while 2.05% per annum for the excess. :)

overrunning is to exceed the proper, desired, or normal quantity, limit, order, etc. btw, in that picture you look like William Hung from American Idol. lol If you don't know who that is, google him. haha

Could it be a cost overrun? This is an unexpected cost?