וְהָיָ֤ה זַרְעֲךָ֙ כַּעֲפַ֣ר הָאָ֔רֶץ וּפָרַצְתָּ֛ יָ֥מָּה וָקֵ֖דְמָה וְצָפֹ֣נָה וָנֶ֑גְבָּה וְנִבְרֲכ֥וּ בְךָ֛ כָּל־מִשְׁפְּחֹ֥ת הָאֲדָמָ֖ה וּבְזַרְעֶֽךָ׃
你的後裔必如地上的塵土，你必向西、向東、向北、向南擴展；地上的萬族必因你和你的後裔得福。
Rashi
ופרצת means AND THOU SHALT BECOME STRONG, like (Exodus 1:12) “the more they became strong".
Rashbam
ונברכו, an expression meaning “refining and improving thereby.” It means that these nations will be improved through intermarriage with your family. כל משפחות האדמה. The word is in a passive, weak mode as I have already explained on the same phrasing in Genesis 12,3