from the course notes:
Sibh - Shiv or Shoo? Most pronunciation differences in Gaelic are fairly mild. However, there are two common ways to say this word:
Sibh (pronounced as shiv) - The most frequently heard in this course by far. Sibh (pronounced as shoo) - Common in Lewis and the North of Scotland. This occurs in a couple of places in the course. Bonus points when you spot it!
Plural "you" is not the same as "they" in English or Gaelic. Sibh is used when you speak to or reference a specific person(s), usually someone right in front of you. If formal (like a parent) or more than one person (friends) and a statement is made to them, you wouldn't use "they." "They" is used for a reference to people who are not a part of a current conversation. The sentence would have used "iad" if the translation was to be "they."