This is a double-replacement reaction. You can predict the products if you rearrange the combination of the two elements. Take the metal of the first reactant with the nonmetal of the second reactant. Then, take the metal of the second reactant with the nonmetal of the first reactant. This is how it happens:
Ca(OH)₂ + 2 HBr --> CaBr₂ + 2 H₂O