This dialog lists all stored log files for the current project. It is only available in the context of a project - i.e. it cannot be used with standalone GEDCOM files.
Log files are only generated in exceptional circumstances. It is quite normal for a project to have no log files. A log file might be generated if, for example, you create a new project and import a GEDCOM file into it which contains errors. One or two log files (usually two) will be created in this case, which will record all errors that were found in the GEDCOM file, and all subsequent corrections that were made to fix the errors.