WordPress at a glance
filter is not described

get_the_excerpt filter-hook . WP 1.0

This filter is documented in wp-includes/post-template.php

Usage

add_filter( 'get_the_excerpt', 'filter_function_name_8882', 10, 2 );
function filter_function_name_8882( $post_excerpt, $post ){
	// filter...

	return $post_excerpt;
}
$post_excerpt
-
$post
-

Where the hook is called

WP_REST_Posts_Controller::prepare_item_for_response()
get_the_excerpt
WP_REST_Attachments_Controller::prepare_item_for_response()
get_the_excerpt
get_the_excerpt()
get_the_excerpt
wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php 1733
$excerpt = apply_filters( 'get_the_excerpt', $post->post_excerpt, $post );
wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php 700
$caption = apply_filters( 'get_the_excerpt', $post->post_excerpt, $post );
wp-includes/post-template.php 429
return apply_filters( 'get_the_excerpt', $post->post_excerpt, $post );

Where in WP core the hook is used WordPress

wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php 186
add_filter( 'get_the_excerpt', 'wp_trim_excerpt', 10, 2 );