Sample Code:

Apex Class:

public with sharing class ContactController {

    @AuraEnabled( cacheable=true )
    public static List < Contact > fetchContacts(){    

        return [
            SELECT Id, Name, Account.Name FROM Contact LIMIT 5
        ];

    }

}

Lightning Web Component:

HTML:

<template>
    <lightning-card>
        <lightning-datatable
                key-field="Id"
                data={records}
                columns={columns}
                hide-checkbox-column="true">
        </lightning-datatable>
    </lightning-card>
</template>

JavaScript:

import { LightningElement, wire } from 'lwc';
import fetchContacts from '@salesforce/apex/ContactController.fetchContacts';

const columns = [
    { label: 'Contact Name', fieldName: 'Name' },
    { label: 'Account Name', fieldName: 'AccName' }
];

export default class DataTable extends LightningElement {

    records;
    error;
    columns = columns;
    draftValues = [];

    @wire( fetchContacts )  
    wiredAccount( value ) {

        const { data, error } = value;

        if ( data ) {
            
            let tempRecords = JSON.parse( JSON.stringify( data ) );
            tempRecords = tempRecords.map( row => {
                return { ...row, Name: row.Name, AccName: ( row.Account ? row.Account.Name : null ) };
            })
            this.records = tempRecords;
            this.error = undefined;

        } else if ( error ) {

            this.error = error;
            this.records = undefined;

        }

    }  

}

JS-meta.xml:

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>52.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__Tab</target>
    </targets>
</LightningComponentBundle>

Output: