Secondary axes are typically used to compare data sets with different scales, with extra axes usually located on the opposite side of the chart.
 Configuring Secondary Axes Copy Link  
An extra axis configuration is needed to associate a secondary axis with the appropriate series, where the keys axis property links the series to the axis.
{
    axes: [
        // x-axis
        {
            type: 'category',
            position: 'bottom',
        },
        // primary y-axis
        {
            type: 'number',
            position: 'left',
            keys: ['male', 'female'],
        },
        // secondary y-axis
        {
            type: 'number',
            position: 'right',
            keys: ['exportedTonnes'],
        },
    ],
}
In this configuration:
- The axis 
keysproperty on the primary axis (left) matches theyKeysof thecolumnseries. - The axis 
keysproperty on the secondary axis (right) matches theyKeyof thelineseries. - The secondary axis has the 
positionofright. 
Any number of additional axes can be added to a chart using the same approach.
For series with multiple keys only a single matching entry in keys is needed.