This component simply renders its children. Why would you want to use such a dumb component? To combine several fields in a single cell (in a <Datagrid>) or in a single row (in a <SimpleShowLayout>).

<WrapperField> allows to define the label and sort field for a combination of fields:

import { List, Datagrid, WrapperField, TextField } from 'react-admin';

const BookList = () => (
            <TextField source="title" />
            <WrapperField label="author" sortBy="author.last_name">
                <TextField source="author_first_name" />
                <TextField source="author_last_name" />

Tip: If you just want to combine two fields in a string, check the <FunctionField> component instead.