Organizations use Sigma to send digital Merits to people to verify their accomplishment. Since only verified, trustworthy organizations are allowed to send Merits on Sigma, those Merits are trusted by other organizations in the world.
If somebody has sent you a Merit through Sigma, congratulations! This means that you have accomplished something meaningful. Many CERTs and other volunteer organizations use Merits to verify emergency response and other crucial training certificates, and licenses.
Merits can mean a lot of different things. There are Merits for completing courses, showing what emergencies people are best equipped to respond to, and more. You can use your Merits to verify that you have a certain skillset. If you have been sent a Merit, that means you have been recognized and verified by an organization on Sigma.