If it fixed number of columns classic cross tab should work:

CREATE TABLE #Temp([File] INT, Main INT, Sub CHAR(2), [Text] VARCHAR(20));

INSERT INTO #Temp ([File], Main, Sub, [Text])

VALUES (1, 1, 'A.', 'hello'),

(1, 1, 'B.', 'SQL'),

(5, 1, 'A.', 'central'),

(5, 1, 'B.', '.com');

SELECT

[File]

,Main

,[A.] = MAX(CASE WHEN Sub = 'A.' THEN [Text] END)

,[B.] = MAX(CASE WHEN Sub = 'B.' THEN [Text] END)

FROM #Temp

GROUP BY [File], Main;

DROP TABLE #Temp;