Where does it say silver certificate on a US 2 dollar bill?

You're very unlikely to find that Wording on any $2 bill you may get in change or from a bank. The last $2 silver certificates were printed in 1891.

The vast majority of $2 bills printed up till 1963 were issued as United States Notes; those printed since then are Federal Reserve Notes. Both types have their designations shown in the banner across the top of the bill's front, as do all other current US bills.