Trojan-Downloader.BAT.FTP is usually a batch script that opens a connection to a remote FTP site (using a built-in Windows FTP client) in order to download one or more files and to activate them.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
Caution: Manual disinfection is a risky process; it is recommended only for advanced users.
To get rid of the batch trojan itself and the files that are downloaded by the trojan, it is enough to delete them from an infected hard disk. Please remember to restart the computer after disinfection.
Such trojans are commonly used my malware writers to update or download malicious files to an already compromised computer.