The section left of the white line in this picture is called a shoulder. This is NOT a cycling lane. It is NOT designed for any vehicles (including bicycles) to use. This area is usually unsuitable for riding due to it’s very rough surface, debris, potholes, ridges, cracks etc. that can damage a bicycle or cause an accident.
Riders should be riding on the road, which is to the right of the line. When the road is clear, riders will usually move toward the darker patches you can see that line up with where a car’s wheels would be. This is the smoothest part of the road with the least debris, allowing a faster and smoother ride.
Please share the road and overtake when safe, rather than expecting riders to leave the road when you approach. If you do see a rider left of this line, they are not sharing the road with you, they have actually left the road completely to allow you to pass.