The \href
take two arguments: the first is the URL to be linked and the second the text showed in the link, so it should be:
\href{http://tex.stackexchange.com/q/275848/71471}{this is my text}
The command do not change the font style in any way, so often it will be already in roman (serifed) font family, that is the default text style in most document classes.
Otherwise, you can change using \textrm{<text>}
or \rmfamily <text>
since the braces of the argument limit the scope of the command:
\href{http://tex.stackexchange.com/q/275848/71471}{\textrm{this is my text}}
\href{http://tex.stackexchange.com/q/275848/71471}{\rmfamily this is my text}
\href
have two arguments:\href{URL}{text}
and write text in a LaTeX font. Please explain what do you mean.\sffamily
to the text part.\rmfamily