It's a derogatory and often childish term, used to describe someone who is perceived as not being tough enough or not willing to stand up for themselves.
Here are some examples of how it might be used:
* "He's such a wussy for being afraid of spiders."
* "Don't be a wussy, just ask her out!"
* "That movie was so wussy, it didn't even have any violence!"
It's important to note that using the term "wussy" can be offensive, especially when used to describe someone's physical or mental health.