can any one explain what below code means

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_ht_litigatio n_ht_mast]') and OBJECTPROPERTY( id, N'IsForeignKey' ) = 1)
ALTER TABLE [dbo].[ht_litigation] DROP CONSTRAINT FK_ht_litigatio n_ht_mast
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_ht_mutation_ Ht_mast]') and OBJECTPROPERTY( id, N'IsForeignKey' ) = 1)...

when i am trying to updating values into newly added column i am getting error which says "Invalid column name 'surveytax'.
Server: Msg 207, Level 16, State 1, Line 3"

pls help me...