Shuv - Turn back (שוב) Means "to return to a previous state or place". See Genesis 3:19 where adam (man), who comes from the adamah (ground) will shuv (return) to the adamah (ground). This verb is often used for "repentance" - turning from a wrong direction to head back in the right direction. Teshuvah is a 40 day "repentance" season before Yom Kippur - to focus on making our relationships right between God and men.

God certainly makes the deal easy for us to understand, "...if my people, who are called by my name, will humble themselves and pray and seek my face and turn [yaSHUVu] from their wicked ways, then will I hear from heaven and will forgive their sin and will heal their land" (2 Chronicles 7: 14) The tradition is that the forty days of Teshuvah came from the experience at Sinai (notice Jesus also spent 40 days in the wilderness, (Mt 4:1).