Numbers are ideal, and I'd think carefully on if there is a metric you can tie to a data point, but it doesn't have to be all about numbers. Example: maybe you

Numbers are ideal, and I'd think carefully on if there is a metric you can tie to a data point, but it doesn't have to be all about numbers. Example: maybe you streamlined a common app flow making it significantly easier for users to accomplish a task, or implemented accessibility best practices across your product making it usable by a wider range of people. Both of these have more pop if there is a statistic you can cite with them, but even without they speak to impact not just "worked on Python web application".