。
The promenade runs parallel to the coast.
Literal
Walking-path [topic-は] coast [with-と] parallel-[adverbial-に] run-[ongoing-ている].
A crisp geometric description. 遊歩道 ('promenade, walking path') is built from 遊歩 ('leisure walking') + 道 (path). 平行 ('parallel') paired with と marks the thing being parallel to. 走っている here is the geometric use of 走る ('to run') for lines/roads — 'to extend, run along.'