What is the translation of "ve'Lo Sachnifu es ha'Aretz"?
Rashi and Targum Onkelos: It means 'Do not render the land guilty'.
Targum Yonasan: 'Do not sully the land', because the shedding of innocent blood spoils the land. 3
Ramban: By flattering the Rotzchim, we flatter the land, which will not produce what it is supposed to - See Ramban, who elaborates, and who quotes the Sifri which cites this Pasuk as the source for the La'av not to flatter.
Ramban: Having included Chutz la'Aretz in the Dinim of Mishpat - (Refer to 35:29:1:2), the Torah here adds a Halachah that pertains exclusively to the inhabitants of Eretz Yisrael, in deference to the Shechinah that dwells there.
See also Na'ar Yonasan, who discusses different versions of Targum Yonasan's wording.
What are the implications of the second half of the Pasuk?
Rashi (in Zevachim, 88b): It implies that, as long as the murderer is not put to death, one is subject to punishment.
Rashbam: It implies that atonement for murder can only be achieved with the blood of the murderer 1 - and in no other way.
Rashbam: Since the word is pronounced "be'Dam Shofcho" with a 'Cholam' (an 'O') and not 'Shafchu' with a 'Kubutz'.