Macromolecule condensation reaction is basically a step or a set of reactions that results in a larger molecule. In this reaction, usually a hydroxyl groups is removed from one of the reactants while a proton is removed from the other. This would then form a water molecule which would be released as a byproduct of the reaction. This should not be confused with a dehydration reaction which also removes water from the system as condensation reactions combine smaller molecules to form a larger one (e.g. a polymerization reaction). The release of water is just a byproduct. In dehydration reactions, the release of water if the main goal of the reaction, usually resulting in a smaller molecule.