Meaning of Portfolio Tracker
These are apps used to monitor trader/investor coins/tokens in one place.
Since a typical crypto trader will likely use 2-5 exchanges, there is need to have their coin/token listed in one place to crosscheck when in Green or Red and reduce stress of monitoring each separately opening all the exchanges.
Examples are Blockfolio, Coincap, Delta, Altpocket, CoinDex, Drakdoo.