Arab= Arabian. Arabic is their main language and alot of arabs also speak other languages. Arabic can be spoken in diffrent "accents" and alot of words are diffrent from one country to another but it's all the same language. For example in the UK we say "Biscuit" in the USA they say "Cookie". Thats just a small example but yeah it's kinda like that a Iraqi might not understand everything a egyptian would say because of their accent.
Anyone who comes from the middle east and north Africa, alot of whom leave all around the world, but orginate from there.
Most of the population is Muslim but you can also get other relgions among Arabs e.g. Christians, Jews and some are ethicists but this is rare.
Warning, not all arabs are suicide bombers!
Seriously like no more than 100 that are alive today are planning to blow something up, and probablly won't anyway.