The sections feature is primarily for use by the printers who print your magazine. Depending on what print process they use (eg web, gravure, etc) their machines print magazines in different-sized sections. So, for example, a 124-page mag could be made up of three sections of 32 pages, plus a section of 24, plus a 4-page section, which is the cover. It’s all bound up together and makes no difference to the reader. It simply depends on the size sections that particular printer’s machines can print.
The sections don't affect your pages. Think of the sections section (sorry) more as a calculator. If you know what sections you want to print on - you can use the calculator to determine whether you created the correct number of pages.
Once you know how many pages you want, and what sizes your printing company can print, you work out how many of each size of section you need. Blinkplan allows for any even-sized section size, and as many sections as you need.