insert value from other table

try this,

ALTER procedure [dbo].[insertproduct]
@Name nvarchar(30),@Model nvarchar(30),@Behcode nvarchar(10)  
as
begin
Declare @H_name nvarchar(30)
set @H_name =(select H_name from House_info where behcode=@Behcode )
insert into House_p (Name,Model,Date,BehCode,H_name)
values (@Name,@Model,GETDATE(),@Behcode,@H_name)
end