Join Tables to Create the Summary View

You need to UNION in the below way. Please note the number of Select columns in each query.

SELECT [SupplierCode]
      ,[Prop Code]
          ,'Rent Received'  AS [FEE TYPE] 
      ,[TotalPayment] AS [AMOUNT]
      ,[Year]
      ,[Month]
  FROM [SQL2012EELearning].[dbo].[CustomerPayment]

UNION ALL

SELECT (SELECT TOP 1 [SupplierCode] FROM [SQL2012EELearning].[dbo].[CustomerPayment] A WHERE A.[PROP CODE]=B.[PROP_CODE]) AS [SupplierCode]
      ,[PROP_CODE] as [Prop Code]
          ,'Repair Cost'  AS [FEE TYPE] 
      ,[AMOUNT]
          ,[Year]
      ,[Month]
  FROM [SQL2012EELearning].[dbo].[RepairCost] B

UNION ALL

SELECT [SupplierCode]
      ,[PROP_CODE] as [Prop Code]
          ,'Supplier Payment' as [FEE TYPE]
      ,[TotalPayment]
          ,[Year]
          ,[Month]
  FROM [SQL2012EELearning].[dbo].[SupplierPayment]

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Regards, RSingh