Data Visualizer is a handy tool to explore what a dataset contains if you're unfamiliar with it. Because this is probably the first time that you have installed Metricbeat, Data Visualizer could be a nice place to visit first, to see the contents of this index:

We can see that the immediate benefits of using Data Visualizer is that it automatically identifies which fields of the index are actually populated (not empty) and also gives the user the ability to see the top values (or a distribution of values) of each field. These will come in handy when deciding which fields to analyze with Elastic ML and which ones to potentially avoid. For example, it is unlikely that the # system.cpu.cores field is useful to analyze with ML because it only has 1 distinct value for all time. Conversely, the # system.cpu.idle.pct field may be useful to analyze with ML.