A Cousin's Code: Settle It!

So I have a younger cousin who’s been hanging out with a group of other teens recently. Unfortunately, my cousin is at the stage where they don’t want to talk about their friends to their parents, so my aunt is freaking out that the group’s all into drugs, or gang wars, or drug-fueled gang wars. I think they just sit around and play video games. Whatever.

Anyway, my aunt rooted through my cousin’s room and found this note from one of their friends (named Nester or something like that). She’s convinced that it’s a map of houses the group is gonna rob or something. I’m fairly sure it’s a message of some sort, but my aunt won’t stop fretting unless I can tell her what’s going on and what the message says.

So, can you find the way to interpret this grid and save my cousin from a preemptive grounding?

For color-blind puzzlers…

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