What does nuclear fusion do?
Nuclear fusion is the fusion of two nuclei (atoms) which, when combined, form a highly unstable element or isotope, which almost immediately breaks up, producing energy and more, smaller nuclei to continue this chain reaction. The energy given of can be harnassed as heat to heat water into steam to turn a turbine to produce electricity, in which case the reaction would be controled, or it can be allowed to go out of control, in which case it would produce a massive explosion.
Yes, nuclear fusion reactions provide nuclear power. But here on earth, we haven't mastered a large scale nuclear fusion power reactor. We can only generate nuclear fusion reactions in a high energy physics lab or in the detonation of a fusion nuclear weapon. Make a note, however, to realize that our sun and most other stars use nuclear fusion to generate their massive power outputs.