Analytics is the systematic analysis of data/statistics. Google Analytics is a tool commonly used by business owners to measure advertising ROI as well as tracking Flash, video, and social networking sites and applications. Familiarising yourself with your analytics gives you the tools to better understand your customers. Google have an academy of free online courses to help you navigate.
However, due to the introduction of Google Analytics 4 (GA4), you really need to upgrade ASAP before July 2023. If you don’t, you’ll lose any existing analytics data, therefore won’t have a reference point to compare traffic to, down the line. Here is the official announcement.