Quite a lot that is racist here. The 'Thomas Kalmaku' character in Green Lantern is an Eskimo/Inuk person originally from Alaska. The character was created in 1960, when Western attitudes towards racial and ethic stereotyping were often less progressive than today. Leading 'hero' figures in comics, films, etc, often had an ethnic-minority assistant or sidekick in a subordinate role (e.g. the Lone Ranger and Tonto)
Eskimo is an old fashioned term for the character's ethnic origin. Eskimo is a collective term used to refer to the Inuit (including the Alaskan Iñupiat, the Greenlandic Inuit, and the Inuit peoples of Canada) and the Yupik (or "Yuit") of eastern Siberia and Alaska.
People in many parts of the Arctic consider Eskimo a derogatory term because it was widely used by racist, non-native colonizers. In Canada's Central Arctic, Inuinnaq is the preferred, and in the eastern Canadian Arctic Inuit. In Alaska Inuk is used. The language is often called Inuktitut.
Grease monkey is a slang term for the occupation of mechanic (he is an aircraft mechanic). A mechanic's job has less status than that of a pilot (e.g. Green Lantern).
Thomas is his forename.
Pieface is his nickname (sometimes alleged to be a racist term from a stereotype of Inuks having round faces). When a person has a nickname it is often shown in brackets or quotes after the first name and before the surname e.g. Michael "Fathead" Harvey, Michael (Fathead) Harvey. In the comic text it is shown slanted.
Kalmaku is his surname (family name).