This is a test of the camera's noise levels. The higher the signal to noise ratio, the greater the difference in strength between the real image data and random background noise, so the 'cleaner' the image will look. The higher the signal to noise ratio, the better.
Sony A6300 signal to noise ratio charts
JPEG signal to noise ratio analysis: The A6300 does an excellent job to match the signal to noise performance of its rivals at its base ISO, and remains strong as sensitivity is raised. Even at the highest settings tested, the readings show it to be very capable.
Raw (converted to TIFF) signal to noise ratio analysis: Despite strong JPEG results, the camera fails to keep up with the competition when raw images are analysed here. Performance is consistent across the sensitivity range, but sadly lower throughout.