Some ISPs and some countries block Tor entry. If Tor Browser cannot connect at all, connects painfully slowly, or the Tor Project site is blocked where you are, a bridge routes your connection through a relay that is not publicly listed as Tor, which hides that you are using Tor.
Open the connection settings, choose to use a bridge, pick the built-in obfs4 option or request one from the Tor Project, and restart. If Tor is not blocked where you are, skip this, because a bridge only adds latency for no gain.
A bridge changes how you reach Tor. It changes nothing about the steps that follow, so verify addresses exactly the same way.