The Breen language was the language spoken by the Breen. To Human ears, it sounded like garbled electronic sounds. Universal translators needed to be adjusted in order to properly translate the syntax. (DS9: "Strange Bedfellows")
Michael Eddington once sent a file info that was intercepted by Benjamin Sisko aboard the USS Defiant. It was a heterophonic, five-line song with an alternating tetrameter and pentameter structure, but other than the catchy tune, it did not mean anything. (DS9: "For the Uniform")
Translated English Edit
Although the universal translator has to be adjusted, when hearing the Breen ,they still do not sound very life like. Their voice is very much like of the way a Vulcan might speak, Although more un lively.
A common phrase said by the Breen; "More prey for the hunt" (War cry in Star Trek Conquest) This assumes their old culture was much of a hunter gatherer society, and takes honour in hunting, much like Earth's native American's.
Sources: Star Trek Conquest