That is roughly ten times what a typical rail-to-rail op-amp delivers, so this part is chosen when the load is low-impedance — think headphone drivers, cable buffers, or actuator pre-drive stages where the op-amp directly sources or sinks significant current without a separate buffer transistor. Gain bandwidth is 2.7 MHz with a 1.57 V/µs slew rate; that is modest by modern standards, but adequate for audio-band or slow-control loops where the high output current is the primary spec.
Supply budget and thermal design
Quiescent supply current is 700 µA for both channels combined. That is the trade-off: you get 320 mA output capability while the amp itself draws under a milliamp, so efficiency is high when the output is lightly loaded or idle. But at full output into a low-impedance load, the package dissipation climbs quickly. The 8-HVSSOP with exposed pad is designed to shed heat into a PCB copper land — the datasheet layout recommendation for that thermal pad is not optional.