How did Meiji Restoration change Japanese government and society?

The country was modernized.

The Meiji Restoration (1868) is called such because it "restored" direct imperial rule, i.e. rule by the Emperor of Japan. The imperial line had existed since at least the mid-6th century, but for much of Japanese history the emperor had been virtually ignored and had no true power in government. In fact, the emperor didn't have much power after the Meiji Restoration either (and none whatsoever now, but that's another story), but the politicians who took control decided to act in the emperor's name in order to validate their actions to the Japanese population and the world. The "restoration" was more like a revolution, but "restoration" has a much more conservative ring to it, and they were trying to depict their efforts as a return to the emperor's proper place in the scheme of things.

Before the Meiji restoration, Japan was a semi-feudal society run by the Tokugawa clan, a lineage of military overlords called the shogun (literally "general"). They had come to power in 1600 after a long period of civil war. Officially, the shogun was "appointed" to his office by the emperor, but the shogunate (that is, the government of the shogun) was the true seat of power and the emperor had no choice in the "appointment." There was a fixed class system with samurai (warrior-aristocrats) at the top, followed by farmers, then artisans (carpenters, blacksmiths, etc.) and at the bottom merchants. As in many pre-modern and early modern societies, the upper crust feared the potential power of merchants, who as a consequence were officially viewed as parasitical and dishonest. There was also an untouchable class known as "burakumin" (literally "hamlet people"). The Meiji Restoration essentially destroyed this entire system. The global implications of this were that a modernized Japan eventually became a world power and by the end of the 19th century joined the game of gunboat diplomacy and imperialism on a par with the West, flexing its muscle in East Asia, which was viewed as Japan's legitimate "sphere of influence" analogous to US intervention in Latin America during the same period.

The new government was composed of lower-ranking samurai from western Japan who had rebelled against the shogun in the name of the emperor, once they had enlisted the latter's support. The class system was officially abolished and Japan established formal diplomatic relations with other countries. The country had been officially isolated by the shogun from the early 17th century out of fear that Western alliances with rebellious feudal lords might threaten the shogunate's power (they were right; by the 1860s the British had been running guns to the guys who finally took over). So basically, Japan became modernized with a central government modeled on those in the West, a standing army, a bureaucracy that anyone could try to join, and (officially) no class distinctions. A parliament was established, but voting rights were at first limited to those who paid a certain amount of taxes, owned land, etc. (Universal male suffrage wasn't introduced until 1925, and women didn't get the vote until just after World War II.) They also adopted new technology such as steam locomotives, the telegraph, and factory automation. There was a lot of Western cultural influence, at first mostly in port cities, that eventually spread throughout Japan. And being a businessman was suddenly a respectable job.

The Meiji Restoration And Modernization

Whole shelves full of books have been written on each of these two subjects. Fortunately for you, the compilers of encyclopedias have narrowed each of the topics down into relatively short articles. Read them. And no, I don't mean that wicky-wacky nonsense online. A real encyclopedia, written and edited by people who have credentials in their academic fields.