It is different than hitting. She's referring to things like art therapy, journaling, possibly music therapy, exercise,etc. These can be seen as constructive venues to deal with emotions rather than destructive. She's encouraging the character to use their right brain (creative) side.
When a person is engaged in hitting a pillow or a punching bag, that creates a pattern in the brain giving the message that displaying anger is an appropriate way to deal with it. Anger can be dealt differently where the person addressing their anger attempts to remain calm and rational rather than worked up (as in the act of hitting an object).
Anger is often a secondary feeling to another emotions i.e. disappointment, fear, shame, etc.