The first two digits mean 60,000 pounds’ tensile strength (which is the ability of a material to resist being pulled apart) per square inch.
The third digit means that the rod can be run in any position, whether it is horizontal, vertical, flat, or overhead.
No one, except those who are strongly familiar with technical welding jargon, really refers to the last digit, but this digit, which is either a 0 or 1, has to do with slag type, power supply, and flux composition.