New Guy Question - How does NextDNS help me?

I installed the nextdns app on my pc and set up the configuration as indicated (recommended, whole system/windows).  Good doc by the way.  My question though, is how does this help me?  I looked thru the logs and it appears my browser is still hitting all these tracking sites (many google, ms, etc).  So if my system is still pinging those sites, I am not sure how my dns is really hidden or secure?  Or do I have to take action and block each one (then see what breaks)?

I know this is likely a stupid question, so please be kinds lol!