to expand on what skidkid said...
There are two types of flight physicals - a 'short form' and a 'long form.' The short form is the yearly physical you have to get by the end of your birth month. It is good for up to one year from the end of your birth month (you can get it the month before, and it will be valid for 13 months.... ie, I was born in Dec, got my annual in Nov, it expires next Dec31).
The long form is done every five years starting with either your 20th or 25th birthday (doubtful it will be the 20th as you probably wont be in Pcola that soon). It's the exhausting one where you see every doc and get all the tests. It's valid for the same period as the short form, b/c it counts as your yearly in those 5yr years (25, 30, 35 ....)
clear as mud?