עַל מַגָן תִּטְלְחוּן לְכוֹן דִתְקַדְמוּן בְּצַפְרָא לְמֶעְבַּד לְכוֹן חֲטוֹף דִי מְאַחְרֵן וְתֵתְבוּן לְמֶעְבָּד זָנוּ דְאָכְלִין מְזוֹנֵי דְמִסְכְּנִין דְלָעוּ בְהוֹן עַל יָאוּת וְכֵיוָן יִתֵּן יְיָ לְרָחֲמֵיהּ דִמְכָא.
1. the bread of travails | לֶחֶם הָעֲצָבִים – The word "הָעֲצָבִים" combines the connotations of labor and pain. Our verse (especially in light of the continuation which speaks of progeny) recalls usage of the root in Bereshit 3:16-17, when Hashem punishes Adam and Chavvah with labor pangs and agricultural work. Others have translated the phrase as "misery's bread", "bread of toil" or: "bread of sorrows".
2. Thus | כֵּן – In other words, Hashem gives His beloved rest in equal measure to the toil of those who work all hours (commentary attributed to Rashbam). Alternatively, "כֵּן" might mean: "indeed" or "true".
3. He gives sleep to His beloved | יִתֵּן לִידִידוֹ שֵׁנָא – This assumes that "שֵׁנָא" is a variant of "שינה", sleep. See Radak similarly that "שֵׁנָא" should be understood as if written "בשינה", "while asleep", or: "with sleep", rendering the verse: "Thus He gives to His beloved in sleep", i.e. without having to work. Cf. J.A. Emerton, "Meaning of séna' in Psalm 127:2," Vetus Testamentum 24.1 (1974): 15-31 who suggests, based on Semitic cognates, that the root "שנא" might mean to elevate or shine, and, as a noun: "elevation" or "success." The following verses then detail the nature of this "success", the merits of bearing children.