The GRE is otherwise known as the Graduate Record Examination, and is not explicit to PT programs but yes - it is the exam you will have to take to be considered for admissions into most programs. Basically, it is a standardized exam that any undergraduate student looking into any sort of graduate program at any graduate school would have to take. It is just a way for admissions committees to get a sense of comparison for each applicant, as we come from starkly different backgrounds and have super unique experiences.
There are three sections to the GRE - reading, math, and writing. A "competitive" score on the GRE is usually about a 300 between both the math and verbal sections, and above a 3.5 (out of 6) on writing. Both the verbal and the math sections are both out of 170 points, so figure getting above a 150 on each of those gets you to 300 and tends to make you more competitive in the eyes of admissions committees. There are a bunch of schools that don't require the GRE at all though (since it's not PT school specific and literally has nothing to really do with what we're going into - oh well), so keep your eyes peeled for those schools if you're interested!
Apply for PT school as early as you can. Definitely take the GRE over the summer (July/August) as long as you have the means to - that way, if you don't get your desired score the first time around, you can comfortably take it and still submit earlier than most applicants (late summer into Septemberish). Some applicants submit in July when it first comes out, but depending on the school, some admissions committees don't even meet until September or so. But it is nice to get all your stuff in and then not have to worry about it! Study flashcards for vocabulary, and go over a couple review books (I recommend the ones directly from ETS - those are what boosted my score!). The studying process should take you like a month-ish and if you study for about this period you'll definitely be okay!
GOOD LUCK!
