The Sicilian is a sharp and flexible response to whites opening move E4. The Sicilian aims to weaken white's control over the center through exchanging a flank pawn for a valuable white central pawn. Additionally the scicilian doesn't force black to immediately commit any of its central pawns to the center which can often allows for a more solid game for black
Watch a video below for an instructive Sicilian Game
Read more about the Sicilian Below
Chess.com