View: Views are user interface elements, i.e. buttons, lists, etc. In Android user interface is specified declaratively in XML.
Activity: Activities encapsulate user interaction with various View elements, in this case a presentation screen, but view-less Activity is possible. Activities can be started by Intent, one Activity can start another Activity. The main program is an Activity.
ContentProvider: Abstracts data as service so that content can be shared and accessed in REST-based manner using URI locators, rather like http requests. This allows uniform means of accessing data without knowledge of structure and implementation. Android provides Sqlite for database access.
Intent: Intent can be thought of as a message broadcast, service or activity request; an "intention" for some action. Intent allows loose coupling of action requestor and action handler.
Service: background process.