Sniffer, Spoofer (generic description).
A sniffer or a spoofer is usually a standalone program to intercept and analyse certain data. For example a sniffer can intercept and analyse network traffic and catch certain data, for example passwords. Trojans sometimes use sniffing capabilities to steal passwords and user information from infected computers.
There also exist a lot of commercial and free sniffers. They can be used to analyse network traffic for perfomance, security issues and faults.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.