Organic Traffic Value is a metric pulled from SEMrush that estimates the average monthly cost to rank for the listed organic keywords in Google AdWords. Basically, it is the value of the keywords that you rank for if you had to pay for that position in Google Ads.
This metric is a good way to put some context around total traffic and total keywords. You (or your competitor) may be ranking for a lot of keywords; however, if the organic traffic value is low, those keywords may have low search volume and less value.
This is a good benchmark to determine relative SEO success between your website and your competitors'.