Fiscally means 'as far as government money is concerned' — taxes, public spending, national debt, the budget. It is the adverb of 'fiscal'. You use it to say from which angle you are judging something: 'The plan is fiscally sound' means the money side of it works, whatever else you may think of it. 'Fiscally responsible' means careful with public money — not spending more than comes in. 'Fiscally conservative' is a very common phrase in politics, and it is worth knowing that it describes an attitude to spending, not the whole of someone's politics; a person can be fiscally conservative and liberal on everything else. This is a newspaper and politics word. You will read it far more often than you will say it, and it sits in business writing too, where it slides a little from 'the government's money' toward 'money matters generally' — 'fiscally strong company'. Purists grumble about that stretch, but everyone understands it. One thing that trips people up: in American English a 'fiscal year' is a company's or a government's accounting year, which often does not start in January. So 'fiscal' there is not always about government at all. Taiwan's 會計年度 is the same idea.