the GPU is 9400M. Its not very good. Probably not gonna do 3D intense more recent games.
It might be good enough for some casual games, or more, depends on each game, I guess. You can always try them out first.
Steam is a digital distribution, digital rights management, multiplayer and communications platform developed by the Valve Corporation. It is used to distribute games and related media online, from small independent developers to larger software houses. Steam also has community features, automated game updates, and in-game voice and chat functionality. (from wiki)