CREATE TABLE table_6633 ("Name" TEXT, "Country" TEXT, "Type" TEXT, "Moving from" TEXT, "Transfer window" TEXT, "Ends" TEXT, "Transfer fee" TEXT, "Source" TEXT)

What transfer window has bra as the country, with 3.4m as the transfer fee?
SELECT "Transfer window" FROM table_6633 WHERE "Country" = 'bra' AND "Transfer fee" = '£3.4m'
SELECT "Transfer window" FROM "table_6633" WHERE "Country" = 'bra' AND "Transfer fee" = '£3.4m'