On your adventure in Port APICO you'll come across a whole host of NPC friends that will help and encourage you on your journey!
NPCs act as a source of lore, but also as shops where you can buy things. As you progress in the game different NPCs will comment on your progress, and let you buy more useful and advanced items!
All NPCs except for Nana Beelia, Ellraiser, and Metakitkat have shops - the shops contain different items based on the NPC, for example Beetrix will sell carpentry and crafting related items.
Like all menu objects, NPCs can actually be picked up with a to be moved to other places (except for Ellraiser, Metakitkat, Moth(ense) and the Merchant)
In the Forests around Port APICO you'll find the first set of NPCs that live in the port, including Skipper and your Nana, plus some other NPCs in the other forest islands.
Out in the dark Swamps all by their lonesome you'll find Abbee, the resident florist.
Out in the freezing Tundra you'll find Bobbee, a blacksmith who tinkers with the mysterious Honeycore crystals.
These are NPCs not specific to a single biome.