By analogy with the oxoanions of sulfur, H2TeO3 would be named?
Tellurous acid. The salts would be called tellurite.
When an element has two oxidation states (valencies) the lower one has an -ous ending and the higher one an -ic ending.
The salts of these acids are called -ite and -ate respectively.
This used to be common also with metal ions:
Iron(II) used to be called ferrous
Iron(III) used to be called ferric
There is a problem when there are more than two possibilities. In this case the prefixes hypo (=under), (hy)per (=above) could be used, like with the oxo-chlorin anions:
The official names for these are now:
monoxo-, dioxo-, trioxo- and tetroxo- chlorate.