When I first arrived in Taiwan in 1991, you could see these six characters in many public places - bus stations, for instance, and government offices. Nowadays, despite the return to power of the Chinese Nationalists (the KMT), this slogan isn't nearly so evident. Read from right to left, the characters literally mean 'May the Republic of China live ten thousand years!' but a better translation would be 'Long live the Republic of China!' The Mandarin pronunciation of 中華民國萬歲 is Zhonghua Minguo Wan Sui.
Some argue that the ROC is long dead, having passed into history when the People's Republic of China (PRC) was founded in 1949. Others maintain it lingered until the 1970s, but lost all legitimacy when first it withdrew from the United Nations (because the UN voted to recognise the PRC as China's legitimate government); and then President Carter severed diplomatic ties between the ROC and the USA.
However, the ROC on Taiwan continues to meet the four criteria of statehood in international law: a permanent population; a defined territory; an effective government; and the capacity to enter into relations with other countries. At the time of writing, 23 countries have diplomatic relations with the ROC, the most important among them being Paraguay and Panama.
I took this photo at the Jianguo Brewery in central Taipei.