How to create multiple meta fields in gutenberg block

It would be better if you included the code that did not work. In any case, I changed your code by adding another text input and a textarea (with relevant entries in attributes and meta).

Here is the modified code. Also, I have changed some of the code to be more readable.

Javascript

( function( wp ) {    const el = wp.element.createElement;    const registerBlockType = wp.blocks.registerBlockType;    const TextControl = wp.components.TextControl;    const TextareaControl = wp.components.TextareaControl;    registerBlockType( 'dc-references-block/dc-references-block', {        title: 'Title',        icon: 'edit',        category: 'common',        attributes: {            blockValue: {                type: 'string',                source: 'meta',                meta: 'dc_references_block_field'            },            // Add two new attributes            name: {                type: 'string',                source: 'meta',                meta: 'dc_references_block_field_name'            },            desc: {                type: 'string',                source: 'meta',                meta: 'dc_references_block_field_desc'            }        },        edit: function( props ) {            const className = props.className;            const setAttributes = props.setAttributes;            // Original element with onChange event as an anonymous function            const text = el( TextControl, {                label: 'write here name of company',                value: props.attributes.blockValue,                key: 'companyName',                onChange: function( value ) {                    setAttributes( { name: value } );                }            } );            //Add two new elements            const secondText = el( TextControl, {                label: 'Write your name',                value: props.attributes.name,                key: 'username',                onChange: function( value ) {                    setAttributes( { name: value } );                }            } );            const textArea = el( TextareaControl, {                label: 'Write a description',                value: props.attributes.desc,                key: 'desc',                onChange: function( value ) {                    setAttributes( { desc: value } );                }            } );            return el(                'div',                { className: className },                // Children of the main div as an array                [ text, secondText, textArea ]            );        },        save: function() {            return null;        }    } );}( window.wp ) );

PHP

register_post_meta( 'page', 'dc_references_block_field', array(        'show_in_rest' => true,        'single' => true,        'type' => 'string',    ) );   // register two new meta corresponding to attributes in JS    register_post_meta( 'page', 'dc_references_block_field_name', array(        'show_in_rest' => true,        'single' => true,        'type' => 'string',    ) );    register_post_meta( 'page', 'dc_references_block_field_desc', array(        'show_in_rest' => true,        'single' => true,        'type' => 'string',    ) );