In the sixth aliyah Moshe tells the Jewish people that the land of Israel is dependent upon G-d for rain to irrigate it and therefore they should know that the land is constantly under G-d's scrutiny. G-d's eyes are on the land of Israel from the beginning of the year to the end of the year.
After that, this aliyah contains the second paragraph of the Shma Yisroel prayer, which we say at least twice a day. (The first paragraph of the Shma was contained in the corresponding same aliyah in last week's parsha, Va'eschanan.) Here we are told that if we heed G-d's commandments G-d will give the proper rainfall to the land and we will have a bountiful harvest. We are told here to put on tefillin, and to put up mezuzahs, both of which contain these words on the parchment contained within them. We are told once again to teach these words to our children and speak of them when we sit in our house, when we walk on the road, when we lie down, and when we get up.