Kibana Timelion is a time-series data visualization tool that offers enhanced flexibility compared to other Kibana visualization types, using a unique syntax to chain functions for complex visualizations. It allows users to plot relationships between different log data, similar to creating a join between uncorrelated logs without fetching entire datasets. Timelion supports a variety of functions, including operators for mathematical calculations, data formatting, and visualization styling, which can be applied to log data retrieved from Elasticsearch instances. Users can enter Timelion through Kibana's main page or visualization section, and can integrate visualizations into dashboards by saving expressions as dashboard panels. Timelion expressions can incorporate multiple data sources, as seen in examples like visualizing cache status, response size by protocol, and high severity logs, offering unique insights that other Kibana visualizations do not.