It's just showing in which datacenter the Durable Object will end up in, if the user hits the one you've selected. colo = colocation, renting space in an existing DC, which roughly equals datacenter yea. The dotted lines go to the place where the DO would be created.
For example if you're in PHL and create a Durable Object, you could end up either in Newark or Ashburn
Hints are a best effort and not a guarantee. Unlike with jurisdictions, Durable Objects will not necessarily be instantiated in the hinted location, but instead instantiated in a data center selected to minimize latency from the hinted location.