These toolbars are visible or available the Curve Editor is open, and in general contain controls for editing animation data in the form of function curves.
Two different Curve Editor layouts are available: standard and classic. The standard layout provides a streamlined interface designed for efficient function-curve editing, while the classic layout offers more tools by default in a familiar arrangement.
Also, the standard layout has Filters Show Hierarchy off by default, while it's on in the classic layout.
To return to this layout from a different one, right-click an empty toolbar area and choose Load Layout Function Curve Layout.
To access the classic layout, right-click an empty toolbar area and choose Load Layout Function Curve Layout (Classic). This layout includes these toolbars:
(upper toolbar)
(lower toolbar)