Behold the kanji character 工. Somewhat resembling a sans serif letter "H" turned on its side, and originally used to represent a tool, it refers to various aspects of labor, functioning as a character in its own right and appearing in other kanji, like 左 (hidari, left), which originally depicted a hand gripping a tool.
In the dictionary, this kanji is commonly read two ways: kō, with an elongated vowel, and ku, with a short vowel. Think of it like this: You can't walk down a street for more than a few meters without seeing a sign reading 工事中 (kōjichū, under construction). Which makes it likely that somewhere nearby, a 大工 (daiku, carpenter), is building a house.
A less common reading is gu, such as in the compound word 工合 (guai), an older reading of 具合 (guai) to mean condition or health, as in 彼は工合が悪いので、会社を休みました (Kare wa guai ga warui node, kaisha o yasumimashita, As he wasn't feeling well, he took an absence from his company).