It means that you enable objects to be accessed through some means. In your examples, you could let the users [create, read, update or delete objects][1] (usually abbreviated to CRUD) using HTTP protocol, using a predefined way to interact with your objects (an API).

That API can adhere to a set of rules - e.g. [RESTful][2] APIs use [HTTP verbs][3], to perform some actions on objects and adhere to some principles that say how resources should be identified/represented and how they should be manipulated through those representations.