This brand name is related to the word "poster".
Postermo has eight letters and three syllables. Leading companies using three syllable names include KFC, Santander and Adobe.
Postermo.com is a dot-com domain. Dot com domains are the most sought after domain extension in the world, famously used by websites like google.com. When most people think of a website, they think of a dot-com.
This domain was first registered in August 2016. Older domains have an advantage when ranking in search engines.