How does it manifest: These planets are the furthest away from each other.  The energies are pulling you in opposite directions. It indicates opposition or conflict. You’re in a meeting and things are getting tense. You’re sitting across from the other person because you might smack ’ em if you get too close 

An example of an opposition in real life: Let’s say your Sun and Mars are in opposition. The Sun is your sense of self. Mars is your drive. One of the manifestations of Sun opposite Mars is that you’re conflicted and might have inner tension. There is friction in expressing yourself and your drive. You may lack the drive needed to go forward.

Do you have an Opposition in your birth chart?