What does SO4 stand for on the periodic table?

'SO4' does NOT appear on the Periodic Table.

'SO4^(2-)' is the sulphate anion. It has a charge of '-2'.

The elements that form the sulphate anion, viz. sulphur(S) and oxygen(O) do appear on the Periodic Table, viz.

No. 8 ; oxygen (O)

No. 16 ; sulphur (S).

NB NO compound appears on the Periodic Table. It is a list of the known elements.