Send appropriate notices to the tenant for late or nonpayment of rent, violations of the rules, etc. Do or oversee evictions. Get your approval for major expenses. Inspect the property occasionally. Provide you with an accounting of all money received and disbursed monthly or quarterly, as well as keep a client trust account for owner money.
State law regulates property managers much as it does real estate agents.
And every state is different. And whatever else you agree upon between you. In fact every responsibility of the property manager is agreed upon contractually. But that is just part of it. Some property managers will charge you a set-up fee, for advertising a vacant unit, for trips to the property.