Masala, in Indian cuisine, just means spices or a mix of spices - although it does sometimes refer to the sauce the spices are used in, like chicken tikka masala. Garam masala is one of many masalas in the Indian kitchen, with garam meaning warm, or hot. The mix is different in every household, but it usually includes the warm flavors of cinnamon and cardamom.
I use cinnamon, cardamom, cloves, cumin, coriander, nutmeg, and pepper, all toasted and ground fine. This mix can then be used in curries, lentils, soups or just sprinkled in some scrambled eggs. The work involved in making your own spice mix is minimal, but the difference is always very noticeable. More