。
He swung one leg out to the other side of the fence.
Literal
Fence [gen-の] far-side [to-に] one-leg [obj-を] swung-out.
向こう側 'the far side / the other side' is a standard directional noun. 片足 'one leg' uses the 片 prefix ('one of a pair'), productive with paired body parts and items: 片手 one hand, 片目 one eye, 片道 one way, 片方 one of two. 振り出す is another compound: 振る 'swing' + 出す 'put out / throw out' = 'to swing out / launch forward.'