Here are some examples of how it's used:
* "Ese hombre es malo." (That man is bad.)
* "El clima está malo hoy." (The weather is bad today.)
* "Esa película es muy mala." (That movie is very bad.)
It can also have the meaning of poor or inferior:
* "Esa comida es mala." (That food is poor.)
* "Su trabajo es malo." (His work is inferior.)
Keep in mind that the context is key to understanding the specific meaning of "malo."