If you mean how nuclear power plants provide energy, the answer is just like any other power plant. The only difference is that conventional power plants burn fossil fuels like natural gas, coal, etc. while a nuclear power plant on the other hand generates heat by the fission of nuclear fuel like Uranium and Plutonium.
The quantity of energy released from the fission of these fuels is millions of times greater than conventional fuels. The heat that is generated is used to run electric turbines which are the same as those used in other power plants. As the temperatures which are possible to achieve and maintain by the fission of nuclear fuels are higher, it is possible to run electric turbines with more efficiency. This means the amount of electricity produced for the same amount of energy obtained from the fuels is higher in the case of nuclear power plants.
Other than the fact the fuel being used and the reaction that the fuel undergoes is different for a nuclear power plant there is not much of a difference in how nuclear power plants provide energy.
All power plants provide energy through the process of electromagnetic induction. A rotor, containing magnets, spins inside a coil of wire and induces a current in the wires. The rotor is spun either through the use of flowing water (hydroelectric power) or by passing high pressure steam through the rotor.
The heat energy to generate the steam is produced either by the burning of fossil fuels such as coal, oil, or natural gas or by the heat generated in a controlled nucear chain reaction.
In a nuclear power plant rods containing a few % U-235 are bombarded with neutrons. Every time a uranium atom splits it forms two smaller atoms, gives off several neutrons, and produces heat energy. By the use of control rods the operators in the power plant either slow down or speed up the chain reaction to produce the desired armount of heat energy and resultant steam to power the generators.
Nuclear power produces about 15-20% of the electricity used in the United States but as high as 80% in France and increasing amounts in many other countries, including Japan.
A nuclear power plant provides energy by the process of nuclear fission. The energy released by this process is millions of times greater than that released by combustion of fuels like gasoline. In this exothermic reaction, a larger atom is split by bombarding it with neutrons, into smaller atoms with the release of a huge amount of heat energy and the release of more neutrons. These can bombard more atoms of the fuel (either uranium 235 or plutonium 239) and causes this to split and release more neutrons. It is a chain reaction, that is a controlled reaction. Unfortunately, highly radioactive wastes are the result of this reaction.