• Content-Aware Fill Workspace: This is the headline feature of CC 2019. Unlike previous versions where content-aware fill was a "blind" guess, this version opens a dedicated workspace allowing you to define exactly which pixels to use and how the fill is applied. It is incredibly powerful for removing objects.
• Frame Tool: This introduced easy masking for images. You can draw a rectangle or ellipse frame and simply drag an image into it, resizing the image within the frame non-destructively.
• New "Home" Screen: Adobe introduced a new start screen with tutorials and recent files. (Note: In preactivated versions, this screen can sometimes be buggy or require patching to disable it).
• Symmetry Mode: This allows you to paint in perfect symmetry, automatically mirroring your brush strokes.
• Blending Mode Preview: You no longer have to guess what "Overlay" or "Soft Light" looks like; Photoshop shows a live preview as you hover over the options.

Cons:

Unlocking Creative Potential: A Comprehensive Guide to Adobe Photoshop CC 2019 v20.0.5

Conclusion

• Create a layer mask: Layer > Layer Mask > Reveal All (Ctrl+Shift+R)
• Edit a layer mask: Use the Brush tool or other painting tools to modify the mask.