HTML:
<template>
    <lightning-card title="LWC Related fields">
        <template if:true={contactRecord}>
        <lightning-datatable record-id={recordId}
         data={contactRecord} columns={columns} key-field="Id">
        </lightning-datatable>
    </template>
    </lightning-card>
</template>
/////////////////////////////////////////////////////////////////////////
J.S
import { LightningElement,wire,track,api } from 'lwc';
import getAccountRelatedRecord from '@salesforce/apex/accountController.getAccountRelatedRecord';
export default class DisplayRelatedFieldsOnAccount extends LightningElement {
@api recordId;
@track contactRecord;

@track columns = [
    { label: 'FirstName', fieldName: 'FirstName', type: 'text' },
    { label: 'LastName', fieldName: 'LastName', type: 'text' },
    { label: 'Email', fieldName: 'Email'},
    { label: 'Phone', fieldName: 'Phone', type: 'Phone' }
];
@wire(getAccountRelatedRecord, { recordId: '$recordId'})
wireConRecord({error, data}){
    console.log('recordId',this.recordId);
    if(data){
        this.contactRecord = data;
        this.error = undefined;
        console.log('recordId',this.contactRecord);
    }
    else {
        this.error = error;
        this.contactRecord = undefined;
        console.log(error);
    }
}

}
////////////////////////////////////////////////////////////////////////////////
WRAPPER CLASS:

public class accountController{
@AuraEnabled(cacheable = true)
public static List<accWrapper> getAccountRelatedRecord(Id recordId){
 List<Contact> conlist = new List<Contact>();
List<accWrapper> acclist = new List<accWrapper>();
    try{
            conlist= [SELECT Id , Lastname,FirstName,Email,Phone FROM Contact WHERE AccountId =: recordId];
system.debug('Showlists>>>>>' + conlist);
            List<accWrapper> aclist = new List<accWrapper>();
            for (Contact cons : conlist){
                accWrapper aw = new accWrapper();
                aw.contactRecord = cons;
                aclist.add(aw);
            }
 return aclist;
} catch (Exception e){
        throw new AuraHandledException(e.getMessage());
    }
}
public class accWrapper{
    @AuraEnabled
    public Contact contactRecord{get;set;}
}
////////////////////////////////////////////////////////////////////////////////////////////this is my table please help me out of this.