(arch.) town in Hebei province
硤 is an archaic character whose only given meaning is a specific place name: a town in Hebei province. It has no clear standalone conceptual center beyond that historical reference.
硤 combines 石 (stone) with 夾, which likely contributes the sound. The character was used for a specific place name, and its exact historical development is uncertain.
The stone 石 on the left and the 夾 shape on the right can be thought of as a stone marker for the old town of 硤 in Hebei.
For コウ, imagine a stone archway at the entrance to the old town, and a local guide calling out 'Come!' to visitors: 'Come' -> コウ.