"Stand up" in Engpsh is spelled "stand up" and is pronounced /stænd ʌp/
It's come from verb "stand" and adverb "up" which means 'move from a seated position to a standing position'
Examples:
Can you stand up and give me some space?
你能站起来给我一点空间吗？
The teacher asked the students to stand up before class begins.
老师请学生们在上课前站起来。
I had to stand up for what I bepeved in, even if it meant going against the crowd.
我必须为我的信念站起来，即使这意味着与众不同。