This is the Render Options Editor. The editor is available from the main menu as Render->RenderOptions, and allows you to control various rendering options such as resolution, shading rate, object orientation, light positions, zoom, and buttons to invoke default or custom renders. (Custom render scripts let you invoke your own scenes to render)
To prevent the ROE from becoming too large, we hid some of the more
advanced functions in the lower portion of the editor, which you can
access by scrolling the editor down...
This is the lower section of the ROE, which lets you change the path to the custom render script, and lets you set frame ranges for rendering multiple frames.
Note that the ROE's window can also be resized, so you can make the window small, so you can just access the buttons you're interested in while taking up a minimum of screen space.