A lycee is a high school, particularly one where French is spoken. Before you enroll at the Sorbonne, you need to graduate from your lycee!
In France, the lycee (or in French, lycée) is the final part of a student's secondary, pre-college education. Generally this means grades 9 through 12, or the equivalent of high school in the U.S. If you attend an American lycee, it is usually a French immersion school, or one that mixes the use of English and French. Lycee derives from the Greek lykeion, an ancient Athenian grove where Aristotle taught.