example.tex

\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}

\usepgfplotslibrary{fillbetween}
\begin{tikzpicture}
    \begin{axis}
        \addplot[name path=function, domain=-1.5:1] {x^2};
        \path[name path=axis] (axis cs:-1.5,0.0) -- (axis cs:1,0.0);
        \addplot[yellow] fill between[of = function and axis];
    \end{axis}
\end{tikzpicture}
\end{document}