It's bad to damage things.
Jill was angry with Amanda as they were arguing with each other.
Jill wants to release her anger.
Jill decides to punch a punching bag and pound a pillow and hit other things that won't break.
Jill starts grabbing nearby things and smashing them on the floor.
Jill eventually calms down and is glad she hasn't caused any lasting damage.
Jill's smashing's cost her so much money that when she's done she's even madder at herself.