וַיִּקְרָ֧א אֶת־שְׁמ֛וֹ נֹ֖חַ לֵאמֹ֑ר זֶ֠ה יְנַחֲמֵ֤נוּ מִֽמַּעֲשֵׂ֙נוּ֙ וּמֵעִצְּב֣וֹן יָדֵ֔ינוּ מִן־הָ֣אֲדָמָ֔ה אֲשֶׁ֥ר אֵֽרְרָ֖הּ יְהוָֽה׃
און ער האָט גערופֿן זײַן נאָמען נֹח, אַזױ צו זאָגן: דער דאָזיקער װעט אונדז זײַן אַ נחמה פֿאַר אונדזער אַרבעט, און פֿאַר דער מאַטערניש פֿון אונדזערע הענט, פֿון װעגן דער ערד װאָס גאָט האָט זי פֿאַרשאָלטן.
Rashi
זה ינחמנו THIS WILL COMFORT US — He will ease from off us (ינחמנו) the toil of our hands. For until Noah came people had no agricultural instruments and he prepared such for them. The earth had brought forth thorns and thistles when they sowed wheat in consequence of the curse imposed upon Adam Harishon: in the days of Noah, however, this ceased (Tanchuma 1:1:11). This is what is meant by the word ינחמנו (viz., ינח מנו). If, however, you do not explain it in this manner, but from the root נחם “to comfort”, then the meaning you give to this expression (connecting it with the idea of “comfort”) will have no application to the name נח, and you would have to call him מנחם “Comforter”.
Chizkuni
זה ינחמנו מן האדמה, “this one will bring us consolation regarding the condition of the earth. Seeing that he had been born after the death of Adam, the curse decreed on earth as being effective during Adam’s lifetime could now be lifted. [According to my calculation Noach was born in the year 1056 after Adam had been created. Seeing that theTorah did not report anyone being born after Lemech, Noach’s father, who was born when Adam was still alive, there is no contradiction here. Ed.]
Ibn Ezra
This one will bring us rest (or “consolation”). Adam informed Lemech through prophecy that his son would bring about the salvation of the world.