Hi Kishore,

You can check this below snippet that has an implementation of showing account and related opportunities in a visualforce page:
 

<apex:page controller="AccContact">
    <apex:form >
        <apex:pageBlock >
            <apex:pageBlockTable value="{!acclst}" var="a">
                
                <apex:column headerValue="Name">
                    <apex:commandLink action="{!selacc}">
                        <apex:param name="conlst" value="{!a.id}"/>
                        <apex:outputText value="{!a.name}"/>
                    </apex:commandlink>
                </apex:column>
                <!--accounts-->
            </apex:pageBlockTable>
            <apex:pageBlockTable value="{!accconts1}" var="a">
                <apex:column headerValue="AccountName" value="{!a.Name}"/>
                <!--contacts-->
                        <!--opportunities-->
                        <apex:column headerValue="Opportunity list">
                            <apex:pageBlockTable value="{!a.opportunities}" var="p">
                                <apex:column headerValue="Opportunity Name">
                                    <apex:outputText value="{!p.name}">
                                    </apex:outputText>
                                </apex:column>
                            </apex:pageBlockTable><!-- End opportunity-->
                        </apex:column>
            </apex:pageBlockTable><!--end account-->
        </apex:pageBlock>
    </apex:form>
</apex:page>


------------------------------Apex Class----------------------------
public with sharing class AccContact {
    
    public list<contact> conlst { get; set; }
    public list<account> accconts1 { get; set; }
    
    public PageReference selacc() {
        string getid=apexpages.currentpage().getparameters().get('conlst');
        accconts1=[select id,name, (select name from Opportunities ) from account where id=:getid ];
        system.debug(accconts1);
        return null;
    }
    
    
    public List<Account> acclst { get; set; }
    public  AccContact (){
        acclst=[select id,name  from account ];
        system.debug(acclst);
        
    }
}

You can use the above apex class that fetches the accounts and related opportunities.

reference: https://developer.salesforce.com/forums/?id=9062I000000XuSyQAK

Let me know if it helps you and close your query by marking it as solved so that it can help others in the future.  

Thanks.