What's "against" mean and when's it used?

Native speaker’s answer
Rebecca
"Against" means in opposition to. It's used in competitions and to express disapproval or disagreement on something. It can also mean being in contact with something or something to lean on something else. Ex: This match is our school against a visiting school! Come and watch us play. Ex: Put the chairs against the wall so more people can sit there. Ex: I'm against you going on this trip by yourself. Ex: I have nothing against the color pink. I just don't like it.