\documentclass{article}
\usepackage{tabularx}% let the table span the textwidth
\usepackage{pdflscape}
\usepackage{lipsum}% for dummy text
\begin{document}
\lipsum[1-5]
\begin{landscape}
\begin{table}
\begin{tabularx}{\linewidth}{XXXXXXXXX}
some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry \\
some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry \\
some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry \\
some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry \\
some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry \\
some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry & some entry
\end{tabularx}
\caption{Some arbitrary caption}
\end{table}
\end{landscape}
\lipsum[1-5]
\end{document}