Meaning: This sentence tells someone to move to an upright position with their feet on the ground in the present moment. It's like saying, "Put your body in an upright position with your feet on the ground right now."
Choice of Words: "Stand" is a verb that means to be in an upright position with one's feet on the ground. "Up" means to move to a higher position. "Now" refers to the present moment or the immediate future. When you combine these words, "Stand up now" becomes an instruction to move to an upright position with one's feet on the ground in the present moment.