[Solved]-Highcharts - second y axis and plotlines in x and y directions-Highcharts

1. Define an array of axes, the second yAxis should be linked to the first one and has the opposite prop:

   yAxis: [{
     title: {
       text: ''
     }
   }, {
     opposite: true,
     linkedTo: 0
   }],
   

2. Set the width of the xAxis grid line to some positive value and, optionally, hide the ticks by setting their length to 0:

   xAxis: {
     categories: [],
     gridLineWidth: 1,
     tickLength: 0
   },
   

Plot lines are like grid lines but more customisable - see docs for more information.

live example: https://jsfiddle.net/fpg0q8ep/