Legend is a list of series and indicators at the top of the chart.
Prices are formatted according to the symbol information - minmov, pricescale, minmove2, fractional.
You can also apply custom formatting using numeric_formatting.
You can hide the legend widget using legend_widget featureset. Edit buttons can be also hidden using featuresets edit_buttons_in_legend, show_hide_button_in_legend etc.
Particular legend elements can be displayed or hidden by default using the overrides.