WordPress at a glance
action is not described

customize_render_section_(id) action-hook . WP 3.4.0

Fires before rendering a specific Customizer section.

The dynamic portion of the hook name, $this->id, refers to the ID of the specific Customizer section to be rendered.

Usage

add_action( 'customize_render_section_(id)', 'action_function_name_6591' );
function action_function_name_6591(){
	// action...
}

Where the hook is called

WP_Customize_Section::maybe_render()
wp-includes/class-wp-customize-section.php 297
do_action( "customize_render_section_{$this->id}" );

Where the hook is used (in WP core)

Does not used.