How to replace sub string by stuff ?

Question

I work on sql server 2012 I need to replace substring by stuff separated stick | 

SELECT DISTINCT
  [InputID],PART_ID,[Vendor ID],Manufacturer,[Digi-Key Part No.] ,[Mfr Part No.],[Description],Category,Family ,Obsolete ,[Non-Stock]
  , [Part_Status],partNumber,CompanyName,DKFeatureName2,[Variant Number],IsUnit,
  SUBSTRING((

     SELECT  isnull(StarFormat,'') + Value+ isnull(endFormat,'')
    FROM #FinalTable
    WHERE ([InputID] = Results.[InputID] and DkFeatureId = Results.DkFeatureId)
    --FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
    FOR XML PATH(''),TYPE).value('.', 'NVARCHAR(MAX)')

  ,1,5000) AS Value--,Results.accepted_value_value
FROM #FinalTable Results
where StatusId=3

and what is meaning of using type.value for xml path