Please explain why primal and dual in such relation?

\begin{tabular}{|l|l|l|l|l|} \hline & \multicolumn{4}{|l|}{ Dual } \\ \hline & & Optimal & Infeasible & Unbounded \\ \hline \multirow{3}{*}{ Primal } & Optimal & V & X & X \\ \cline { 2 - 5 } & Infeasible & X & V & V \\ \cline { 2 - 6 } & Unbounded & X & V & X \\ \hline \end{tabular}