Many options, Google Analytics is very common.
https://analytics.google.com/analytics/web/
Very easy to implement in Bubble (free and commercial plugins available)
Pixel (facebook) another option
http://forum.bubble.io/t/authenticating-users-tracking-activity/152816
There are plenty of alternatives - depends what you are after, privacy? spending budget? 
https://www.semrush.com/blog/google-analytics-alternatives/
Full disclosure - I make a GA4 plugin.
https://bubble.io/plugin/google-analytics-4-single-page-apps-1617143385310x480056316420948000