I am developing an app where I need a panel like the one shown below. The left panel shown in the second image slides in from the left when the user presses the plus icon next to the English dropdown. What is this element and how can I recreate it? This is a Windows 8.1 C# XAML app.
There is no standard control to do all of that. Use a Grid and define an animation for the fly-in is the easiest option.
UWP (Win10) has a control to do this, called a SplitView control. More information on that an how to use it can be found on MSDN.
Martin