Перед свадьбой ей долго поправляли брови, потому что одна бровь выглядела темнее другой.

Before the wedding, they fixed her eyebrows for a long time because one eyebrow looked darker than the other.

Breakdown of Перед свадьбой ей долго поправляли брови, потому что одна бровь выглядела темнее другой.

• потому что: because
• перед: before
• выглядеть: to look
• ей: her

Questions & Answers about Перед свадьбой ей долго поправляли брови, потому что одна бровь выглядела темнее другой.

Why is свадьбой in the instrumental case after перед?

Because the preposition перед meaning before takes the instrumental case when it refers to time or position.

So:

• свадьба = wedding
• перед свадьбой = before the wedding

This is a fixed pattern you should learn:

• перед уроком = before the lesson
• перед работой = before work
• перед встречей = before the meeting

So перед свадьбой is completely regular.

Why is ей used here? What case is it?

Ей is the dative singular form of она.

• она = she
• ей = to her / for her

In this sentence, ей долго поправляли брови literally means something like they were adjusting her eyebrows for a long time or her eyebrows were being worked on for a long time.

The person receiving the action is often put in the dative in Russian, especially in sentences like:

• Мне помыли голову = They washed my hair
• Ему лечили зуб = They treated his tooth
• Ей поправляли брови = They were touching up her eyebrows

So ей does not mean she is doing the action. It means the action is being done to/for her.