Plot[Sin[2 Pi x], {x, 0, 3},
PlotRange -> All,
PlotRangePadding -> {Automatic, {Automatic, .2}},
Epilog ->
Inset[Graphics[{
Arrowheads[{-0.07, 0.07}],
Arrow[{{.25, 0}, {1.25, 0}}],
Text[Style[" Period ", Background -> White], {.75, 0}]}],
{.75, 1.05}]]
