Al-Sham is the classical Arabic term for Damascus and its hinterlands, and over time, it came to denote the area between the Mediterranean and the Euphrates, south of the Taurus Mountains and north of the Arabian desert.
What country is Sham?
Sham is the historic Arab name for what you might call Greater Syria. In English and French, the old name for that region is the Levant, which is where the letter 'L' comes from in ISIL. The term Levant first appeared in medieval French. It literally means "the rising," referring to the land where the sun rises.
Why is Syria known as Sham?
The early Arabs referred to Greater Syria as Bilad al-Sham; in Arabic al-Sham means left or north. Bilad al-Sham is so called because it lies to the left of the holy Kaʿba in Mecca, and also because those who journey thither from the Hijaz bear to the left or north.