Regrettably, it appears this equation is incorrect. Hg3Se2 is mercury(II) selenide, a compound of mercury and selenium. Whereas, Hg2Se2 is not a recognized chemical compound. In other words, there is no compound with the formula Hg2Se2. Moreover, this equation isn’t balanced due to the loss of oxygen atoms.
This could be a case of a typing error or a misunderstanding of chemical compounds. More accurately, the reaction equation could be:
This equation describes the reaction of mercury(II) selenide with oxygen to produce mercury(II) oxide and selenium.
If you require additional information about this specific chemical equation, please provide more complete and accurate details.