English Explanation of Pirkei Avot 1:2

Shimon the Righteous was one of the last of the men of the great assembly.
He used to say: the world stands upon three things: the Torah, the Temple service, and the practice of acts of piety.
The mishnah begins by noting that Shimon Hatzadik (the righteous) was one of the last men of the great assembly, which was the last link in the chain of the transmission of oral Torah mentioned in mishnah one. In other words, Shimon Hatzadik lived long before the time of the mishnah, and is not really part of the rabbinic period. He is one of the few people whose name is remembered from this period of Jewish history.
There are two interpretations of Shimon Hatzadik’s statement that the world could not stand without these three things. The first is that he means that the world literally could not exist without these things. These three things are the three legs upon which the world rests. Another interpretation is that it was for the sake of these three things that the world was created.
According to the rabbis, without Torah the world could not exist. Without people continuing to study Torah, God would destroy the world, for the study of Torah is one of the purposes of creation.
The word used to denote Temple service in the mishnah is “avodah”, literally worship. When the Temple stood, it was through the merit of the worship performed there, that God brought rain upon the earth (see Deut. 11:13-14). Without this worship, the world could not continue to exist. When the Temple was destroyed, prayer took its place.
There are two other interpretations to the word “avodah” in the mishnah. The first is the performance of mitzvoth in general. The second interpretation is literal work, plowing, harvesting etc. The idea behind this interpretation is that God gave the world to human beings so that they would tend to it and thereby become God’s partner in creation. If human beings were to cease acting as God’s partner, God would cease his role as well.
Gemilut hasadim, acts of loving kindness, are not merely acts of charity, but any act that helps another person in his time of need (visiting the sick, comforting the mourner, welcoming guests). The rabbis teach that these acts are even greater than giving charity, for a person gives charity with his money, but these acts are performed with money and by the person’s own body.
We should also note that according to Rabban Yochanan ben Zakai, after the destruction of the Temple acts of loving kindness take the place of the Temple service that can no longer be performed. Whereas in the past a person would be atoned through sacrifices, after the destruction the way to achieve atonement was by the performance of acts of piety.