My brother immigrated to Korea. He sent me an invitation. How come? Is it for the government? Or a travel agency.

The invitation letter is used to help you apply for a Korean visa. This is not for our China government or travel agency.

Your brother sent you the original invitation. If you entrust a travel agency to apply for a visa, you can pass it on to the travel agency.

If you apply to the embassy yourself, you should give it to the Korean embassy yourself.

I suggest you consult the travel agency for all kinds of materials needed to apply for a Korean visa. An invitation letter is not enough to apply for a Korean visa.