Juice was any beverage obtained from a liquified food, such as oranges, apples and grapes.
In 2152, Jonathan Archer offered Keyla some juice, which she accepted. (ENT: "Two Days and Two Nights")
In 2372, Benjamin Sisko was surprised that his son Jake ordered raktajino and makapa bread instead of juice and oatmeal. Jake explained that Kasidy suggested it. (DS9: "For the Cause"
The term "juice" could also refer to energy (ENT: "The Communicator", "Anomaly (ENT)", DS9: "Q-Less"), while "out of juice" meant lacking energy. (DIS: "Kobayashi Maru", "The Examples", TNG: "Samaritan Snare")
To "get the (creative) juices flowing" meant to become inspired. (VOY: "Riddles", "Worst Case Scenario")
To "juice up" was to improve how well something worked. (TNG: "Interface")
To "give (something) more juice" was to increase power to it. (VOY: "Prototype")