In a word, yes.
The label is telling you that if you attempt to draw more than 52A from the 12V rail, then the power supply will not be able to maintain 12V out.
The label doesn't say what will happen. There's a few choices:
- Smoke and flame,
- Blown Fuse,
- Tripped circuit breaker
- Operates at reduced voltage,
If it's a fuse, it may be replaceable, or maybe not. If it's a circuit breaker, it may re-set itself after a cool-down period, or you may have to reset it manually.
The most desirable behavior is foldback. That's where the power supply senses the over-current, and shuts itself down to an "idle" state. You re-set it simply by turning it off and then back on again.