What is Kalam according to Islam? I have already checked the Wikipedia entry about it but it is still vague to me. Please explain this concept with examples.
'Ilm al-kalam as one of the Islamic sciences, discusses the fundamental Islamic beliefs (Allah is One, Prophethood etc.) and doctrines which are necessary for a Muslim to believe in. It explains them, argues about them, and defends them.
Ilm al-kalam is the study of Islamic doctrines and beliefs. In the past, it was also called "usul al-Din" or "'Ilm al-tawhid wa al-sifat".
Divine Justice, predestination, free will, Prophet hood, Divine Attributes are some subjects of Kalam. Islamic Philosophy and Kalam are very much intertwined.
The linked article gives an overview about Ilm al-kalam, its history and development mainly from a Shia perspective, but explains the view of other schools of thought as well.