A
path created with the Pen tool does not become an image element
until you stroke or fill it. The Fill Path command fills a path
with pixels using a specified color, a state of the image, a pattern,
or a fill layer.

Path selected (left) and filled (right)
Important: When you fill a path, the color values appear
on the active layer. Make sure that the layer you want is active
before beginning. You cannot fill a path when a layer mask or text
layer is active.