This feature allows you to backup the MySQL Binlogs (a.k.a "Binary Logs") in real time and upload them to your Amazon S3 archive.
The binlogs keep a record of all statements that made any changes to your database in the order they occurred. This is an important difference from a mysqldump backup, which represents a full "Logical Backup" of your database structure and content at the time of the backup. Binlog backups allow you to recover and / or undo individual statements which have happened after your last full mysqldump backup.
For best results, configure your MySQL Dump backup jobs to "Flush Logs" so a fresh binlog file will be started after each MySQL Dump backup.