Using acmart.cls 2022/02/05 v1.82 Typesetting articles for the Association for Computing Machinery
from latest version of the Primary Article Template - LaTeX
In the included file sample-acmsmall.tex
it was added \usepackage{rotating}
before \begin{document}
and this code in the section Tables to simulate a large table you have to turn it.
\setlength\rotFPtop{0pt plus 1fil}
will center the table laterally.
\setlength\rotFPtop{0pt plus 1fil} % added <<<<<<<<<<<<
\begin{sidewaystable}
\centering
\caption{Frequency of Special Characters}
\label{tab:freq}
\begin{tabular}{*{14}{c}}
\toprule
A &B &C& D &E &F &G &H &I &J &K &L &M \\
\midrule
0.4 & 2.447 & 2.177 & 2.304 & 4.921 & 4.298 & 2.121 & 3.928 & 3.478 & 3.462 & 1.751 & 0.875 & 0.525 \\
0.8 & 4.894 & 4.354 & 4.609 & 9.843 & 8.597 & 4.241 & 7.857 & 6.957 & 6.924 & 3.502 & 1.750 & 1.049 \\
1.2 & 7.341 & 6.530 & 6.913 & 14.764 & 12.895 & 6.362 & 11.785 & 10.435 & 10.386 & 5.252 & 2.625 & 1.574 \\
1.6 & 9.789 & 8.707 & 9.218 & 19.686 & 17.194 & 8.482 & 15.713 & 13.914 & 13.848 & 7.003 & 3.500 & 2.099 \\
2 & 12.236 & 10.884 & 11.522 & 24.607 & 21.492 & 10.603 & 19.642 & 17.392 & 17.310 & 8.754 & 4.375 & 2.624 \\
2.4 & 14.683 & 13.061 & 13.827 & 29.529 & 25.791 & 12.723 & 23.570 & 20.871 & 20.772 & 10.505 & 5.250 & 3.148 \\
2.8 & 17.130 & 15.237 & 16.131 & 34.450 & 30.089 & 14.844 & 27.498 & 24.349 & 24.234 & 12.256 & 6.125 & 3.673 \\
3.2 & 19.577 & 17.414 & 18.435 & 39.372 & 34.388 & 16.965 & 31.427 & 27.828 & 27.697 & 14.006 & 7.000 & 4.198 \\
3.6 & 22.024 & 19.591 & 20.740 & 44.293 & 38.686 & 19.085 & 35.355 & 31.306 & 31.159 & 15.757 & 7.875 & 4.723 \\
4 & 24.471 & 21.768 & 23.044 & 49.215 & 42.984 & 21.206 & 39.283 & 34.784 & 34.621 & 17.508 & 8.750 & 5.247 \\
4.4 & 26.919 & 23.945 & 25.349 & 54.136 & 47.283 & 23.326 & 43.212 & 38.263 & 38.083 & 19.259 & 9.625 & 5.772 \\
4.8 & 29.366 & 26.121 & 27.653 & 59.058 & 51.581 & 25.447 & 47.140 & 41.741 & 41.545 & 21.009 & 10.500 & 6.297 \\
5.2 & 31.813 & 28.298 & 29.957 & 63.979 & 55.880 & 27.567 & 51.068 & 45.220 & 45.007 & 22.760 & 11.375 & 6.821 \\
5.6 & 34.260 & 30.475 & 32.262 & 68.900 & 60.178 & 29.688 & 54.996 & 48.698 & 48.469 & 24.511 & 12.250 & 7.346 \\
6 & 36.707 & 32.652 & 34.566 & 73.822 & 64.477 & 31.809 & 58.925 & 52.177 & 51.931 & 26.262 & 13.125 & 7.871 \\
\bottomrule
\end{tabular}
\end{sidewaystable}
with this output

Not related: The acmart document class includes the booktabs package for preparing
high-quality tables. It recommends to use \toprule
, \midrule
and \bottomrule
instead of \hline
.
\documentclass
,\begin{document}
,\end{document}
, and by telling us which packages are needed to compile your test code.