It is very difficult to understand... and not able to get logic behind this query..

DECLARE @Text NVARCHAR(500);
DECLARE @StringDelimiter CHAR(1);

SET @Text = 'This T-SQL will split these sentences into rows.' +
'How many rows will be returned?.' +
'M.a.y.b.e..n.o.n.e.?';
SET @StringDelimiter = '.';

-- Add delimiter before and after text;
-- This removes the need for special code to handle start and end of string.
DECLARE @TextPlus NVARCHAR(502)
SET @TextPlus = @StringDelimiter + @Text + @StringDelimiter;

WITH Tally(Number) AS
 (SELECT 1 AS Number
  UNION  ALL
  SELECT Number + 1 AS Number
  FROM   Tally
  WHERE  Number < LEN(@TextPlus))
SELECT   SUBSTRING(@TextPlus,
                   Number + 1,
                   CHARINDEX(@StringDelimiter, @TextPlus, Number + 1) - Number - 1) AS SPLIT
FROM     Tally
WHERE    Number <= LEN(@TextPlus) - 1
AND      SUBSTRING(@TextPlus, Number, 1) = @StringDelimiter
ORDER BY Number
OPTION  (MAXRECURSION 0);