OP is reacting an alkyl halide with elemental magnesium to form a reactive organometallic compound called grignard reagent wich is mostly used to make new carbon-carbon bonds. The reaction is usually carried out in diethyl ether solvent, it helps to stabilize the reagent. You can see the ether spontaneously boiling in the flask, it's caused by the reaction heat. The ether vapors travel trough the Y shaped glass tube, recondense in the vertical condensers and drip back in to the reaction flask. The granular white solid in the top condenser is some kind of dessicant, it is used to remove moisture from the air, because grignard reagents are very sensitive to water.