Translation:Korea is beautiful.
i remember the word beautiful because of monsta x's beautiful /아룸다워. maybe it helps you too. :)
한국 means Korea in general. That's how most South Koreans refer to it in regular conversation. If you want to make the destinction, 대한민국 is South Korea and 북한 is North Korea.
조선민주주의인민공화국 - Democratic People's Republic of Korea; 조선 - Korea by n. Koreans, 남조선 - s. Korea by n. Koreans, 북조선 - n. Korea by n. Koreans (rarely used)
대한민국 - Republic of Korea; 한국 - Korea by s. Koreans, 북한 - n. Korea by s. Koreans, 남한 - s. Korea by s. Koreans (also rarely used)