Some Roku features on both players and TVs will not be available outside the US. While Brazil is an officially supported country by Roku, there are still features that won't work there.
I assume you are referring to receiving over the air (OTA) television? Did you buy the TV there locally, or from an online source. Be aware that Brazil uses the Integrated Services Digital Broadcast-Terrestrial (ISDB-T) standard for broadcast, which is completely different than the ATSC 1.0 standard used in North America. If you bought an ATSC TV, it will not work for OTA broadcasts in your current location.
Your TV should work with most streaming apps, but what Roku labels as "live TV" is a streaming service, and might not be available outside the US.
