#the people of the east

This means the people of Paddan Aram, which is a land east of the land of Canaan.

#and, behold, three flocks of sheep were lying there by it

The word "behold" marks the beginning of another event in the larger story. Your language may have a way of doing this.

#For out of that well

This phrase marks a change from the story to background information about how the shepherds watered the flocks. (See: [[:en:ta:vol2:translate:writing_background]])

#they would water

"the shepherds would water" or "those taking care of the sheep would water"

#the well's mouth

Here "mouth" is a way of referring to an opening. AT: "the opening of the well" (See: [[:en:ta:vol1:translate:figs_idiom]])