Through the years, the Saxons, Angles and Jutes mixed their different Germanic dialects. This group of dialects forms what linguists refer to as Old English or Anglo-Saxon. The word "English" was in Old English "Englisc", and that comes from the name of the Angles. The Angles were named from Engle, their land of origin.
Before the Saxons the language spoken in what is now England was a mixture of Latin and various Celtic languages which were spoken before the Romans came to Britain (54-5BC). The Romans brought Latin to Britain, which was part of the Roman Empire for over 400 years. Many of the words passed on from this era are those coined by Roman merchants and soldiers.