A sonnet written by Shakespeare almost always has 14 lines and is written in the iambic pentameter. This means there are 3 quatrains (4 line sections) and one "heroic" couplet. The rhyme scheme, therefore, is ABAB (1st quatrains), CDCD (2nd quatrain), EFEF (3rd quatrain), and GG (heroic couplet).
I hope this helps!