I ran into this slang occasionally. Does this mean something (normally a number, e.g. KPI, index etc) is growing? slowly or fast? where does this slang come from?
Mapmakers (especially European and North American mapmakers) have historically and traditionally oriented their maps in a "North up" configuration, where north is at the top of the page relative to the written words. Graph makers have also traditionally oriented the axes of charts to show positive trends at the top of the page.
From that, people have equated "north" with "up" on paper, so it became common to refer to positive and negative trends with north and south.
Tilting refers to a line that has changed angle slightly, and north indicates it is now heading towards the top of the chart.