* -logy: This suffix indicates a study or science of something. For example, "biology" is the study of life, "geology" is the study of the Earth, and "sociology" is the study of society.
* -urgy: This suffix indicates a process or technique related to something. For example, "surgery" is the process of operating on a patient, "metallurgy" is the process of working with metals, and "liturgy" is the process of public worship.
Therefore, "gy" itself doesn't have a specific meaning, but it often forms part of larger suffixes with specific meanings.