Your real estate agent advises you on how to present your property. If necessary, your agent will advise cleaning, repairs, storage, "depersonalization", reorganization of furniture, sometimes even going so far as to use the services of a professional stylist. This is called home staging and can be called "residential valuation" or "real estate valuation". The goal is to improve the image of a property in order to sell it.
When buying your Realtor can source off-market deals and sometimes properties that are not publicly listed. Your real estate agent can also help you negotiate better to get a better deal. They can also help you have your offer accepted before other buyers.