First of all, the one in the left is the most electronegative element. The first letter of an element must be in uppercase letter

So, in ionic compound, e.g., Metal + Nonmetal compound (Sorry for the comment, it is wrong), you name it with the suffix -ide with the element in the right hand side. Example: Sodium Chloride

Another is the  covalent compound, e.g., Nonmetal + Nonmetal compound. you name it with numerical Ancient Greek word before the element name and add the suffix -ide in the right hand side element. Example: Dihydrogen Monoxide
i dont get it why CuSO4 became copper II sulfate help me plssss
why Ag3PO4 became silver phosphate?
Because the anion copper has an 2+ charge and the cation SO4 has 2- charge
When criss cross this is Cu2 (SO4)2, however the principle says that this is invalid and can be solved by eliminating therefore we have the compound CuSO4
ohh thankyou so much i got it!! :)