I came across this symbol in an IEC standard and don't know exactly what it means. From the circuit is appears to be a generic load, but does it have any other significance?
That looks like a gas discharge tube. These are used for over voltage protection. Gas filled tubes dissipate large voltage transients making them suitable for lightning protection applications such as in telecom circuits.
The symbol is similar to one that is used for a TVS diode which is also used for similar purposes.