[Plugin: Events Manager] Change some wording

you can try this snippet and paste to your theme functions.php;

function my_em_change_text( $translated_text, $text, $domain ) {
	switch ( $translated_text ) {
		case 'Spaces' :
				$translated_text = __( 'Available Seat', 'dbem' );
				break;
		case 'Price' :
				$translated_text = __( 'Cost', 'dbem' );
				break;
	}
	return $translated_text;
}
add_action( 'gettext', 'my_em_change_text', 20, 3 );