This system, supported by CSIRO, works by giving audio cues to cattle through solar-powered smart collars as they approach the fence and a small electric pulse if they continue on. Over a short period of time, the cows learn to turn away when they hear the audio.

If they do go as far as receiving the pulse, it's significantly less than the shock of an electric fence, minimising any stress and ensuring welfare of the animals. Cleverly called eShepherd, it can be used on properties to reduce expensive fencing and keep stock out of areas that are difficult to muster or control.
https://blog.csiro.au/turns-can-teach-old-young-cows-new-tricks/