A property portfolio is simply an assemblage of properties owned or developed by a particular company or individual. If a company is making references to its property portfolio, then this means that the company is referencing those properties on which it has previous performed work.
For example, the Westfield Group mentions that its property portfolio spans 119 shopping centers around the world. Each of these shopping centers would be one element of its overall property portfolio. Real estate developers will often have a property portfolio which explains and provides property information for all of the property which they have developed or are currently in the process of developing.
Real estate agents might even have a property portfolio which might contain property information about the properties which they are attempting to sell.
Most private individuals not involved with real estate on the professional level will not have any form of property portfolio, as these individuals will likely own one or two pieces of real estate, if any, and they will not need to easily and quickly present the property information of these pieces of real estate property as might a real estate professional with a property portfolio.
A company might also be interested in expanding its property portfolio by buying or becoming involved with new properties, in order to better improve its stature and prestige. The property information of properties in a property portfolio will generally include the address of those properties, the acreage of those properties, the cost of those properties, and any developments that have been built on those properties.