The Frase Topic Score, found in the "Optimize" tab, is the key component of Frase's Content Optimization workflow (screenshot below).
Frase recommends topics by analyzing the top Google results for your keywords and performing NLP analysis over them.
In a nutshell, Frase extracts content from each URL and then leverages proprietary Named Entity Recognition to extract topics.
Each time one of these topics is added to your editor, another mention will show in the score. So if "social media platforms" is 0/1, but then it gets mentioned once, the score will read 1/1 and your Topic Score will increase. The right side number is the average number of times the topic is mentioned across its sources, while the left side number is the number of times it's mentioned in the Frase editor.