In SQL Server, the REPLICATE function repeats the string the specified number of times. In PostgreSQL, you can use the REPEAT function.
SQL Server:
-- Repeat 'ab' 3 times SELECT REPLICATE('ab', 3); # ababab
PostgreSQL:
-- Repeat 'ab' 3 times SELECT REPEAT('ab', 3); # ababab
For more information, see SQL Server to PostgreSQL Migration.