속에

In a sentence

• 책상 속에 책이 있어요.

  There is a book inside the desk.

  Here, '속에' is used to indicate that the book is located within an enclosed space, the desk.

• 그의 마음 속에 행복이 가득해요.

  Happiness is full inside his heart.

  In this sentence, '속에' specifies the inner emotional or metaphorical location, within his heart.

• 숲 속에 동물들이 살고 있어요.

  Animals are living inside the forest.

  The phrase '속에' describes the space physically encapsulated, the forest, housing animals.