what is the use of {children} props of Layout - reactjs

Question

Below i have mentioned two code snippets one for Layout and another one of signup.here i used layout because i am going to use different layout for different pages. here my question is, what things of signup.js are taken by {children} props of Layout???
i am unclear about the use of children props, please give me clarifications
if some more clarification needed about code then please comment.
Layout.js
import React from "react";
import Menu from './Menu';
const Layout = ({ title = "Title", description = "Description",className="col-md-12",children}) => (
<div>
<Menu />
<div className="jumbotron">
<h2>{title}</h2>
<p className="lead">{description}</p>
</div>
<div className={className} >{children}</div> {/* without children in page there not show any form fields */}
</div>
);
export default Layout;
Signup.js
import React, { useState } from "react";
import { Link } from "react-router-dom"; //example of use in sign in link after signup
import Layout from "../core/Layout";
import { signup } from "../auth";
const Signup = () => {
const [values, setValues] = useState({
name: "",
email: "",
password: "",
error: "",
success: false,
});
const handleChange = (name) => (event) => {
setValues({ ...values, error: false, [name]: event.target.value }); //error false becoz when we donnot submit any thing and submit click it gives error but after type again
//error message disappear
};
const { name, email, password, success, error } = values;//to make thing easier we distructure here
const clickSubmit = (event) => {
event.preventDefault(); //when button clicked page going for reload we don't want so we use this
setValues({ ...values, error: false }); //when it is submitted we want set to previous error false
signup({ name, email, password }).then((data) => {
if (data.error) {
setValues({ ...values, error: data.error, success: false });
} else {
setValues({
...values,
name: "",
email: "",
password: "",
error: "",
success: true,
});
}
});
};
const signUpFrom = () => (
<form>
<div className="form-group">
<label className="text-muted">Name</label>
<input
onChange={handleChange("name")}
type="text"
className="form-control"
value={name} //when handle chenge happened handleChange method runs is update state what is the value of state that will be value of input field
/>
</div>
<div className="form-group">
<label className="text-muted">Email</label>
<input
onChange={handleChange("email")}
type="email"
className="form-control"
value={email}
/>
</div>
<div className="form-group">
<label className="text-muted">Password</label>
<input
onChange={handleChange("password")}
type="password"
className="form-control"
value={password}
/>
</div>
<button onClick={clickSubmit} className="btn btn-primary">
Submit
</button>
</form>
);
const showError = () => (
<div
className="alert alert-danger"
style={{ display: error ? "" : "none" }}
>
{error}
</div>
);
const showSuccess = () => (
<div
className="alert alert-info"
style={{ display: success ? "" : "none" }}
>
New account is created. please <Link to="/signin">Signin</Link>
</div>
);
return (
<Layout
title="Signup"
description="Sign up to Node React E-commerce App"
className="container col-md-8 offset-md-2"
>
{showSuccess()}
{showError()}
{signUpFrom()}
</Layout>
);
};
export default Signup;

Answer 1

Children prop is an array of components that is Layout's child
Example
<Layout>
<ComponentA />
<ComponentB />
<Layout/>
So the children prop will be an array like this [<ComponentA />,<ComponentB />]

Answer 2

When passing data to a component, there are two methods:
Pass data as props - this is used when you are passing known data types
Pass data as children - this is used when you need more flexibility
When you pass data as props, you can assign a custom name like this:
<Layout
title="Signup"
description="Sign up to Node React E-commerce App"
className="container col-md-8 offset-md-2"
/>
In the second method, everything within component is called children. In your case, showSuccess(), showError(), signUpFrom() are considered as children, and they will be rendered where you have the children inside <Layout/>