Yes, a Nuclear reaction known as Nuclear Fusion reaction takes place in the Sun.
The sun provides both heat and light energy. These two energy arises due to the Nuclear fusion reaction that happens inside the core of the Sun. This specific type of reaction that occurs insides the sun is called Proton-Proton Fusion Reaction.
Nuclear Fusion in the Sun
In the core, hydrogen is converted into helium by nuclear fusion. As it takes four hydrogen atoms to fuse into each helium atom.
In this reaction, the Photons in the proton-proton reaction. The hydrogen nuclei are transformed to helium nuclei by a number of chain reactions.
During this process, some of the mass is converted into energy.
A nuclear reaction in the Sun
Sun fuses about 620 Million metric tons of hydrogen every second and produces 3.8 x 1026 J of energy per second.
This energy gets decreases when it reaches the earth. The Sun intensity on earth is about 1.4 kilojoule per unit area in unit time.