Hello! I need help with this science questions. Thank You!

2. One of the reasons E=mc^2 is important to us is because it explains how our sun produces huge amounts of energy through nuclear fusion of hydrogen atoms. Use this example to describe the relationship between the mass of the hydrogen atoms and energy that is produced.

Please help me. I have no clue what it is. Thanks!

It is thought that two isotopes of hydrogen (D or deuterium + T or tritium) fuse to form helium.

H^2 + H^3 ==> He^4 + n^1 + energy.
The mass of the D plus the mass of T is greater than the mass of the He formed. The so-called mass deficiency is converted to energy. That is in the form of heat and light. Here is a web site where you can read more about it.
http://en.wikipedia.org/wiki/Nuclear_fusion