It adds on to the QEP (Quebec Education Plan) and facilitates lesson planning, because it lays out in detail what students learn and when. There's a nice video describing what the symbols mean, and it's a really handy resource to have when planning long-range. I use it to provide end goals (i.e. what I want the students to understand and demonstrate), but it also shows the progression, which is nice because you don't end up putting the cart before the horse.
Unfortunately, I did not get a copy of the progression, because I am still a student, and not yet on the board's list. Turns out that they've got everything posted on their website. Hooray! However, you need to know how to do an advanced web search just to find the documents, because they do not seem to be listed in the English section of the MELS site.
If you're not too familiar with how to do that, just follow the link to http://www.mels.gouv.qc.ca/progression/index_en.asp which will give you the progression of learning for elementary school. There's also one for high school, available at http://www.mels.gouv.qc.ca/progression/secondaire/index_en.asp.