Its not directly on the sea (although not far away). Their goal in the south will be to take Odessa, which means having Kherson (and its small airport) will be a valuable logistical staging point from which to first take Nikolaev (which is 30 minutes away by car), then position themselves to attack Odessa from the east. At that point, I would imagine the amphibious forces the Russians have just off the coast of Odessa will attack from Black Sea, and the 1,500 or so troops Putin has in Transnistria will attack from the west to surround the city.