Fiscal conservatism is an ideology based on reducing the amount of money that governments get through taxation while simultaneously reducing spending. People who believe in fiscal conservatism feel that taxes put a strain on the economy and that governments are generally too large anyway. They favor downsizing government services in order to make tax breaks financially feasible. There are also some fiscal conservatives who are more concerned with balancing government spending with taxation so that there isn't a debt.
Self-described fiscal conservatives usually hold a fundamental belief that people should be able to keep their own money so that they can decide what to do with it. Many think the government is essentially stealing their freedom by seizing their money and making their decisions for them about the best way to use it. Most people who follow this philosophy are willing to allow for a certain amount of taxation, but usually for very limited purposes such as national defense or policing. Some take it even further and oppose any kind of taxation, especially when the tax is taken involuntarily. They would generally favor sales taxes over something like a national income tax.
Some believers in fiscal conservatism also think that reducing taxes can actually increase government revenues in the long run. Those who hold this view think that putting more money into people's hands will result in so much economic growth that it will more than compensate for any revenue lost from tax cuts. This is one of the main aspects of fiscal conservatism that is widely opposed by those who disagree with the philosophy, and they point to examples where it has led to increased government deficits as proof that it doesn't work. Overall, this issue is very contentious and carries heated disagreement on both sides.
Another major concern for fiscal conservatives is usually spending. In the same way that they consider taxation anti-freedom, they often see government spending programs as a way of exerting control over the populous. Many of these individuals would prefer social services and help for the poor to come through voluntary charity instead of through governmental aid.
For some fiscal conservatives, it's not really a question of taxation or spending, but instead an issue of basic accounting. For example, they may actually favor raising taxes if that was required to keep government debt under control. These people think it's important that the government be run in a profitable way like a good business, so they may favor spending cuts along with tax increases in combination. This approach can be hard to sell politically because it's focused on long-term goals instead of short-term benefits.