"stance" = "a way of standing" (Webster's dictionary definition) "To take a stance" is to take a position on an issue, so that everyone knows which side you're on. You might sign a petition for or against something. You might join a picket line and parade around with a sign letting people know in no uncertain terms where you stand.

To take a stance is to have an opinion and let it be known. Some politicians take a stance that does not represent the will of the people they represent. They are following their own judgment. I let my opinion be known today. The stance I took was that the tests were to difficult because they did not represent the information covered in class nor in the book.

"Cheryl wanted her company to merge with its competitor. She took a pro-merger stance." "Robert was wary about the merger. He took an anti-merger stance." You can get the feeling of the phrase by imagining how Cheryl and Robert may be standing at the business meeting. Cheryl approves of what is happening, so she may be eagerly leaning forward over the conference table reviewing documents with her arms out. Robert is scared, so he may be standing towards the back of the room with his arms crossed, leaning on his back foot (almost like he is getting ready to run away). By reading Cheryl and Robert's body language (or stance), you can get an idea of what their "stance" is on the merger. As a more extreme example, take a look at this karate fighter's stance: http://meaningness.com/images/mn/karate_stance_588786_500x438.jpg You can tell by the way he is standing that he intends to fight rather than run. He has "taken a stance" on how to handle the person running towards him. He will fight, not run.

I'm sick of letting people at work just use my milk all the time for their coffee!!! I would normally back down and not cause trouble but this time I'm taking a stance!! I'm sick of it!! You should take a stance if you believe in what you're talking about, like the old saying, by - I believe - Malcolm X says, "If you don't stand up for something, you'll fall for anything."