Get Field Count using Aggregate Function:

List<AggregateResult> ui=[Select  count(loan__Rejection_Reason__c) cnt,count(loan__Reversal_Reason__c) cnt1,count(Failure_Reason__c) cnt2,loan__Loan_Account__c from loan__Loan_Payment_Transaction__c where loan__Rejection_Reason__c !=null group by  loan__Loan_Account__c];
for(AggregateResult ar: ui)
{
    //loan__Loan_Payment_Transaction__c lt = new loan__Loan_Payment_Transaction__c();
   
    String str = '' + ar.get('loan__Loan_Account__c') ;  //Get profileId
    String str1 = '' + ar.get('cnt') ; 
    String str2 = '' + ar.get('cnt1') ;
    String str3 = '' + ar.get('cnt2') ;//Get count of Id using the alias name
    System.debug('##########'+str);
    System.debug('$$$$$$$$$$$'+str1);
    System.debug('%%%%%%%%%%'+str2);
    System.debug('&&&&&&&&&&'+str3);
  }