What are deeds of heart?

Assalamualaikum, i actually wanted to know what is deeds of heart? I heard a lot of scholars say that if a person doesn't have deeds of heart, he basically doesn't have faith, so what is good deeds of heart, and what are bad deeds of heart, do they mean a person's intention or his believe it things like a person's believe in islam, and things like that, are they called deeds of heart?