\documentclass[a4paper]{article}
\usepackage{lmodern}
\usepackage{amssymb,amsmath}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{hyperref}
\usepackage{booktabs}
\begin{document}
\thispagestyle{empty}

\begin{table}[h]
  \begin{tabular}{lll}
	\toprule
	Animal & Food  & Size \\
	\midrule
	horse  & hay   & large \\
	frog   & flies & small \\
	fooboar  & \multicolumn{2}{c}{unknown} \\
	\bottomrule
  \end{tabular}
\end{table}

\end{document}