生 is life (in a fresh sense, similar to the word for lettuce, 生菜life vegetable), and 抽 is short for another word for soy sauce抽油, smoky sauce or smoky oil. So 生抽 is fresh soy sauce or life smoky oil.
About This Dish
Light Soy sauce, specifically Chinese light soy sauce (different from Japanese light soy sauce), is a thinner and lighter, but saltier, soy sauce, that is the default soy sauce used in cooking.