en_tn/gen/10/19.md

border

This could be translated as "territory."

from Sidon, in the direction of Gerar, as far as Gaza

The direction south can be stated explicitly if needed: “from Sidon and went in the direction of Gerar in the south as far as Gaza town” or "from Sidon city in the north as far south as Gaza town, which is near Gerar.” (See: rc://en/ta/man/translate/figs-explicit.)

and as you go toward Sodom, Gomorrah, Admah, and Zeboiim, as far as Lasha

The direction "east" or "inland" can be stated explicitly if needed: "and then east toward Sodom, Gomorrah, Admah, and Zeboiim towns, as far as Lasha” or "and then inland toward Sodom, Gomorrah, Admah, and Zeboiim, as far as Lasha”

These are the sons of Ham

The word "these" refers to the people and people groups who were listed in verses 6-19.

by their languages

"broken up according to their different languages"

in their lands

"in their homelands"