They hide away specifics of the microprocessor byte coded language so that you may concentrate on what you are trying to achieve rather than how to represent it in a specific computer architecture.
Java is one such language,developed in 1995 by James Gosling who was at that time working for Sun Microsystems.
All High level languages come with a set of common stuff you need called Libraries(i.e Java Class Libraries).
Java is used to develop mobile applications(Android apps) ,web applications and Internet data manipulation. It is a fourth generation language and like most high level languages it is architecture neutral and instructions are much closer to human and or English language.( i.e print(); -an instruction to print out on the console).