Is h2so4 base salt or acid?

No such substance is 'h2so4'.

If you mean ' H2SO4 ' , then this is Sulphuric Acid.

As the name suggests it is an ACID , neither a base nor a salt.

However, the sulphate anion ' SO4^(2-) '

, when combined with a metal , forms a salt .e.g. Copper sulphate (CuSO4) a chemical salt.

NB When writing chemical formula; single letter elemental symbols are ALWEAYS a CAPITAL letter.

Hence

Hydrogen is ' H '

Sulphur is ' S'.

Oxygen is 'O'

Two letter elemental chemical symbols are always, first letter a CAPITAL letter, and the second letter is small/lower case; e.g. sodium 'Na' (Nadium ; Latin).

This is the international standard and therefore understood 'world wide'.