What does this statement mean? - Lā ilaha illa al-Lāh

What does this statement mean? – Lā ilaha illa al-Lāh

 I was always under the belief that it means "there is no god but god" Today I saw a  post saying that it is "there is No god but Allah". I am confused now.

Now which one is correct? Please provide accurate answers.

Apt replies had already been poured and enough references are available on net. But still I’d like to present my view on the topic. But let me tell you I won’t dare to delve deep into etymology like zanaz because I’ve no sound knowledge of Arabic leave alone its complex linguistic data.
Literally it means
La=no; ilaha=one who can be worshipped, Almighty; ila=except; allah= Allah
So as you see there is difference in ilahi and Allah. According Islamic viewpoint Allah can be ilahi, but any other creature or power which may be regarded by non-muslims as ilahi (Just like Zeus or rahma) can’t equal Allah.
Just as you pointed out earlier Allah has a more ancient origin and was originally used by people of Arabia to refer to the major deity just as indicated by the name of Abdullah, the prophet’s father. Although Islam claims to be the global religion it certainly has strong Arabic influence. So Allah, which was already present in the Arabic vocabulary was used for referring to the Almighty, and the rest of the minor Gods were discarded.
As you know Islam is monotheistic at the core it has only one Almighty. So “Gods” in polytheistic religions like the Greco-Roman religion or Hinduism in its present form (Sanatana dharma has only Brahma as the sole God) can’t be compared to “Allah”. That’s what it says. All Gods except the Allah (God as depicted in Islamic mythology) are fake. Then again if we look at monotheistic religions like Abrahamic religions (Christianity, Judaism) and others then we can conclude that Islam claims that the Gods in those religions are also not to be believed since Islam is “Exclusive” too. And Islam claims all Abrahimic religions to be its predecessor so it says since it is the newest version, it has to be followed and the older ones be ditched (But tell me why people are “UPGRADING” to Windows XP from Windows Vista….. Ow…sorry for relating such nonsense).
Islam in fact has a test for the status of “GOD”. This test is depicted in the 3rd chapter beginning from the end, one which reads “Kulho allahus samad. Lam yulid…”. Any creature or power that satisfies these tests will be taken as the Allah by Muslims. These include that He (wrong term from Islamic standpoint) can’t be the the son or daughter of anybody; that He is genderless and that He has no wife (or husband) or offsprings. All Greco-Roman and Hindu deities fail in this test. And so on. Finally it will be obvious that there can be only one God, i.e- Allah. Even though the Gods of some religion might pass the test there is an Extra! Islam reinstates that the Almighty be called only Allah or by the 99 other names He has. However for reference or ease of understanding He may be referred to as God.
So I hope this little article (call it a mess) clears up the things.
PS—Justic; I laugh at people when they say they can convert people into Muslim just by making him/her chant Kalma-e-shahadat (La ilaha…). You have to believe in all the basic believes of Islam (including the existence of Jinns and that Sun goes round the earth) and not just that You take Allah as God and Mohammad (PBUH) his apostle. I consider those brats who go round the streets and miss their Namaz (Salat) and Roza (fasting) as non-muslims….Oops…I’ve been going overboad. I myself miss a lot of Salats….