What is the significance of an apostrophe?
An apostrophe can signify possession of one or many things, it can be a contraction, it can be a quote inside a quote, or simply a quote.
Example: Ruth's bike was stolen.
^ The bike was Ruth's, and we know that because there is an apostrophe.
Example: The animals' food was destroyed by humans.
^ There are multiple animals, and they all have food. So, it signifies that there are multiple animals that have food.
Example: You're getting on my nerves.
^ The word "you're" signifies the word "You are."
Quote inside a quote -
Jim said, "The other day, someone said, 'I like Jake.'"
^ As you can see, if there is a quote inside a quote, then you use an apostrophe. In British English, you would just use an apostrophe instead of a quote
Example: Jake said, 'I really like you.'