entity framework with stored procedure

Your stored procedure is incorrect.

alter PROCEDURE [dbo].[select_value]
    -- Add the parameters for the stored procedure here
    @Keyword varchar(1000) output,
    @ResultHead varchar(1000) output,
    @Year int
     
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
 
    -- Insert statements for procedure here
    SELECT @Keyword=keyword, @ResultHead=resulthead from SeoAnalysis where YEAR= @Year