\documentclass{beamer}

\setbeamercolor{mycol}{bg=gray}

\begin{document}

\begin{frame}
\begin{beamercolorbox}[center]{mycol}
\begin{columns}[totalwidth=.9\linewidth]
\begin{column}{.8\linewidth}
some text that is long and spans multiple lines still not long enough maybe now let's see argggh no I need at least three lines so keep rambling a bit longer until three lines are reached just to notice that 4 lines are better or even 5
\end{column}
\begin{column}{.15\linewidth}
\includegraphics[width=\textwidth]{example-image}
\end{column}
\end{columns}
\end{beamercolorbox}
\end{frame}

\end{document}