Hi
Your screenshot shows Photoshop working normally. Where the mask is white the image on the layer is visible. Where the mask is black the image on the layer is transparent.
If you want the mask to reverse, click once on the mask to highlight it then press Ctrl+I (Cmd+I on Mac). This will invert the mask.
If you want part of the masked image to show so that you can further develop the mask and are working in a recent version of CC e.g. CC2017, set preferences >Tools and check Double Click Layer Mask Launches Select and Mask Workspace.

Then double click the mask which will launch the S&M workspace. You can set view to Onion Skin and transparency to 50% and continue to adjust the mask.

Dave