This is normally the first screen you will see when you start the app. From here you can listen to your music and adjust the playback and listening options. The exact look will vary depending on the screen size, skin (theme), and Settings that you have chosen, but the principle remains the same.
Broadly, the Player Screen shows song information and artwork in the upper part of the screen, then a middle section for the main playback controls, and finally the app's main Navigation controls at the bottom.
Cover Artwork: swipe left or right to change to the previous or next track ; tap or swipe-down to view the current song within its Library Category (e.g. in its Album, Folder, etc view) ; swipe-up for lyrics (if available) ; long-press for a menu of further context-related choices.
Icon controls: top-right Chromecast ; bottom-left Rating (as Thumb-Up or Thumb-Down by default) ; bottom-right three-dots context menu (same function as long-press on artwork)
You can use options in Settings=>Look and Feel=>Player UI to declutter the display by hiding the Chromecast button, or the three-dots menu button, and switching from 'Thumb' ratings to regular five-star ratings. You can also use Settings=>Look and Feel=>Skin to reposition the Title and Artist/Album boxes to be shown beneath the cover artwork instead (enable 'Alternative Layout').
Next is a row of several control buttons. From left to right: Visualization (generates patterns in time to the music) ; Sleep Timer ; Track Counter (optional, via Settings=>Look and Feel=>Player UI=>Show Track Counter) ; Repeat ; Shuffle. Tap each icon to cycle through the available options, or long-press for a pop-up list.
There is a separate Guide to using the Repeat and Shuffle modes, which are very comprehensive but can take a bit of getting used to.
Next comes the main Player Controls (aka "Pro Buttons"). From left to right: Previous Category (e.g. last Album, Folder, etc) ; Previous Track ; Play/Pause ; Next Track ; Next Category (e.g. next Album, Folder, etc). You can press-and-hold on the Track buttons for Rewind or Fast-Forward functionality. For a better understanding of the term "Category" as it is used in Poweramp, see the Categories/Queue Guide.
The thin bars behind the control buttons are called the Waveseek area which you can drag left or right to make adjustments to the playback position within the track. This can also be shown as a simpler bar, configured via Settings=>Look and Feel=>Skin=>Seekbar Style.
Elapsed Time and Total Duration indicators are beneath the button area. Long-press on Elapsed Time to return to the start of the track.
The final info at the bottom is Metadata. Tap to cycle through various different pieces of technical information, or long-press to see the 'Audio Info' chain which shows how the sound has been processed from source file to output device.
The bottom row is the always-present Navigation Bar. From left to right: Library (to browse through your music collection in various view styles) ; Equalizer (frequency-response adjustments) Search ; Menu (including Help and Settings)