BSX5.DLL definition, relationships, removal:

BSX5.DLL is a dynamically linked library. In simple phrase, it is an essential component of a particular parasite. Most threats depend on such libraries and wouldn't work without them. The BSX5.DLL file can be responsible for the dangerous payload a parasite carries, so deleting it will definitely reduce all the security and privacy risks.
The BSX5.DLL file is installed and used by BookedSpace adware.
You are highly advised to scan the system, delete the BSX5.DLL file and all related objects.
Please note that the BSX5.DLL file actually may be a fully legitimate part of the operating system or legitimate software. Often parasites use files with unsuspicious names, but malicious functionality. You should always carefully check the file before deleting it. It may not be related with malware, but can be required by your essential programs to work properly.