Be honest- your Mac's screen is cluttered with windows from all the apps you have open. Sometimes it's handy to view a couple simultaneously, but having too many apps visible can be incredibly distracting. There are a variety of ways to focus on a single app at a time, but here's one of the easiest:
When you click on a window or dock icon to bring it to the foreground, hold down the Option key to hide all the other windows from various apps you have open.
If you get in the habit of Option-clicking to switch apps/programs regularly, before long you'll find it easier to focus on what you're doing without all the distractions from the other apps. Buckle up: Productivity, here we come!