Malo vs. Mal

Malo is an adjective and Mal is an adverb.
So if you are modifying a noun, use malo/a, mal will tell how something was done or how someone feels.

Malo/a: Bad

La pobreza es tan mala

Ella es una mala persona

Poverty is very bad

She is a bad person


Mal: Badly, Poorly

Me siento muy mal

Te has portado mal

I feel very badly (poorly)

Yo have behaved badly (poorly)