GRE = Graduate Record Examination. Required for many post-baccalaureate programs.
It seems to be different depending on which type of program and the caliber of schools you're applying to. Most of the time, the GRE is not that important - recommendations and undergraduate work are usually more important, and as long as your GRE score isn't super low (1150 is fine) it probably won't affect you either way. For Communications, well, I'm not really sure, but since she took it without much preparation, taking it again after some practicing could really help.
Also, there is no longer an Analytical section, there is now Analytical Writing - 2 timed essays. The writing is on a scale of 1-6.
I took the GRE 2 months ago, and I scored: Verbal 650
, Quantitative 780
, Analytical Writing 4.0
...that's what I get for being a science major. Never written a timed essay in my life before practicing for this darn test.
I'll be applying to Biochemistry programs at good schools, probably not Harvard, but Brown, Tufts, Wisconsin, possibly UChicago, possibly even Johns Hopkins. For Biochemistry PhD programs, the basic GRE is required pretty much to make sure you understand English and can do basic math. Undergraduate work, recommendations, and research experience are MUCH more important.
I wish her luck!