These are miscellaneous settings that control how products are handled by the catalog and cart systems. The Product module provides the limit on the number of rows on each page of the product lists, as well as the settings for the "Add to Cart" form.
If product kits are enabled, there is also a setting that determines how the customer sees them in the shopping cart. Kits may be seen as a unit or individual products. The Order module will always see individual products, but future modules may apply discounts for kits, and it would be bad if the customer put a kit in the shopping cart and then removed half of it and still got the discount.
Product nodes contain a variety of information about the items being sold, but not everything is of interest or use to the customer. The display of these fields in the view tab of the product may be disabled here. The way nodes are formatted by Drupal is ultimately up to the theme, but the default theme function uses these settings to configure the display. Product template files will be able to find all of a product's fields in the $content array.
Not every product in the store is cut from the same mold. Some products sold might be services, downloads, or access to exclusive content. In addition, products might have certain properties (like 50% with a specified coupon) that other products don't have. To accommodate this, Ubercart allows you add product features to a product. Any module (e.g. the Ubercare core modules File Downloads & Roles) that make use of product feature will have its settings here.