"not so much" is an expression that is used in the following structure:
1) a sentence about something positive
2) a mention of something else, ending in the expression "not so much."
This means that the second thing is very bad.
For example:
The weather yesterday was nice. Today, not so much.
Here's a paragraph from the news:
A Conference Board of Canada report puts Canada's three oil-rich provinces - Alberta, Saskatchewan and Newfoundland and Labrador - on top of the world in terms of economic performance. The rest of Canada, not so much.
