Literally: tire(d) – labor – distress – fatigue
Alternately: Complete and utter exhaustion. As tired as one can be.
Notes: This is another compound of redundant terms for emphasis: both 疲労 and 困憊 mean “exhaustion,” “fatigue,” “weariness.” I should probably mention that the first term is by far the more common, and I’ve never even seen the final character before in my life.
憊 is read on its own as hai; be careful when voicing it in the compound, because bai (which some people might guess) is considered an error.