Arbitrary anchors can be placed in a document with hyperref's hypertarget,
and then referenced with hyperlink -- see LaTeX/Hyperlinks.
\documentclass{article}
\usepackage{hyperref}
\begin{document}
\section{mytitleone}%2 5 7 is supposed to be here by refference.
\hypertarget{mytarget}{}% Empty target caption
\section{mytitletwo}
\hyperlink{mytarget}{2}
something.
\section{mytitlethree}
\hyperlink{mytarget}{5}
Something.
\section{mytitlefour}
\hyperlink{mytarget}{7}
Something.
\end{document}
Output (links shown with a red box):

Edit - After a comment exchange established that OP essentially wanted functionality provided by the label command in this answer. I've added a variant of this command which doesn't print any text (see below). Example:
\documentclass{article}
\usepackage{hyperref}
% From https://tex.stackexchange.com/a/54857/172926
\makeatletter
\newcommand*{\textlabel}[2]{%
\edef\@currentlabel{#1}% Set target label
\phantomsection% Correct hyper reference link
#1\label{#2}% Print and store label
}
\makeatother
\makeatletter
\newcommand*{\mylabel}[2]{%
\edef\@currentlabel{#1}% Set target label
\phantomsection% Correct hyper reference link
\label{#2}% Store label
}
\makeatother
% Example for OP
\begin{document}
\section{First section}
\begin{table}
\begin{tabular}{l|l}
Section & Reference\\\hline
2& \ref*{section2number}\\
3& \ref*{section3number}\\
\end{tabular}
\end{table}
\section{Second section}
\mylabel{3}{section3number}
\section{Third section}
\textlabel{7}{section2number}
\end{document}
\mylabel{3}{name} creates a label called name which provides a value of 3 (for example) when referenced. \textlabel{7}{name} functions in a similar way but also prints the value at the labels location.
Output:
