M = {{2, 8, 1}, {7, 3, 4}, {5, 6, 9}}
MatrixForm@M

TableForm[M, TableAlignments -> Center,
 TableHeadings -> {{"r1", "r2", "r3"}, {"s1", "s2", "s3"}},
 TableSpacing -> {4, 2}]

Grid[M, Frame -> {{Red, Purple, Red}}, Alignment -> Right,
 Background -> Pink]

Plot[{Sin[x], Cos[2 x]}, {x, -\[Pi], \[Pi]},
 PlotLegends -> "Expressions", GridLines -> Automatic,
 PlotStyle -> {Directive[Blue, Thick], Directive[Red, Dashed]}]