\documentclass[a4paper]{article}
\usepackage{fontspec}
\usepackage{polyglossia}
\newfontfamily\devanagarifont[Script=Devanagari]{Lora Devanagari}
\newfontfamily\englishfont[Script=Latin]{Lora}

\setmainlanguage[numerals=devanagari]{hindi}
\setotherlanguages{english}

\begin{document}

$body$

\end{document}