Maimonides explains that “The only difference between our life today and during the Messianic Era is that we are now subjugated by the kingdoms.” In other words, the main characteristic of the Messianic Era is that the Jewish people will rest from oppression by other nations.
Nachmanides disagrees with Maimonides. In his opinion, the Messianic Era will involve a substantial change in people’s spiritual life, in particular concerning free will. During the Messianic Era, choosing good will be inherent to human nature and the evil inclination will no longer exist. Humans will return to the state of the first man before his sin, when good was innate to him, and he had no evil inclination or desire to do evil. Man will innately only wish to do good, because he will not desire anything else.
During the Messianic Era, everyone who opens G-d’s Torah will discover secrets of Creation and secrets of the Heavenly Throne. During this period, knowledge, wisdom and truth will bubble over;  and the entire world’s sole desire will be to know G-d.
The Jewish people will have great sages who know mystical matters, and who possess knowledge of their Creator. 
The Aruch Laner writes that in those days, Moses, Aaron and their sons would be resurrected to instruct the people on the proper path as they did during the exodus from the land of Egypt. 
All the righteous of Israel who died in exile waiting for salvation will be resurrected with them. They will wake up and sing with them. 
Daniel said about this period, “Fortunate are those who wait and reach those times.” 
Maimonides in the Laws of Repentance writes that not only Israel but the entire world will be rectified in G-d’s Kingdom,  and the whole creation will be elevated spiritually. For instance, if in the future a person tries to pick a fig on Shabbat, the fig will scream out loud: “Shabbat!” 
According to the holy sources, it seems that spirituality will infuse the world during the Messianic era. May we merit it speedily in our days.
 Rabbi Moshe ben Maimon (Maimonides), Mishneh Torah, Laws of Repentance 9:2
 ibid. Laws of Kings, 12:5.
 Rabbi Yaakov Ettlinger, Aruch Laner, Nida 11b
 Taanit 30b.
 Daniel 12:12.
 Mishneh Torah, Responsa 11:4.
 Midrash Tehillim 316.