The Term "A La Carte" literally means "from the menu." In Reference to Cable Television, A La Carte means that the customer would be able to purchase channels separately, without choosing a package.
A La Carte pricing tends to be more expensive than package pricing. For example, if you went to a fast food restaurant and ordered a burger, fries and a drink separately, it would be much more expensive than if you bought the value meal.
There are some groups that are demanding that Satellite and Cable companies be required to sell, individually, each of the channels that they carry. While many think that this would save them money (being able to only choose what they want), it would actually end up being more expensive and leave them with fewer choices.