A property manager's role is to look after the management of your rental property/ies.
Their services can usually be as minimal or as comprehensive as you like, depending on your preferences.
A full-service property manager will identify and screen tenants for your property, conduct regular inspections of your property and manage all tenant dealings, including maintenance requests.
A property manager cannot comment on the suitability of an investment to your personal circumstances unless they are also a QPIA.
Investors should only deal with a property manager who has the appropriate state real estate licensing. PIPA membership is also highly desirable.