Who is the uncle of Moses?
Moses' parents were Amram and Jochebed. "Now Amram took for himself Jochebed, his father's sister, as wife; and she bore him Aaron and Moses. And the years of the life of Amram were one hundred and thirty-seven" (Exodus 6:20). In other words, Amram married his aunt. Hence, you could say that Amram was both Moses' father and his cousin, though we usually only consider the closer relationship.
Amram's brothers were: Izhar, Hebron, and Uzziel. "And the sons of Kohath were Amram, Izhar, Hebron, and Uzziel. And the years of the life of Kohath were one hundred and thirty-three" (Exodus 6:18). Hence, these three were Moses' uncles on his father's side of the family. Kohath was Jochebed's brother.
Kohath's other brothers were Gershon and Merari. "These are the names of the sons of Levi according to their generations: Gershon, Kohath, and Merari. And the years of the life of Levi were one hundred and thirty-seven." Hence, on Moses' mother's side of the family, Moses' uncles were Gershon and Merari.
A problem does occur when matching this genealogy with the length of time Israel stayed in Egypt. There are strong indications that some generations were skipped. If this happened, then we don't know Moses' uncles precisely as we don't know where the skipped generations occurred. See "How Long Was the Egyptian Bondage?" for more information.