This is the 1995th most frequent Russian word.
третье
"Третье" means "third" in English.
Here, 'третьем' is used as the ordinal number 'third', inflected in the prepositional case due to its grammatical function in the sentence.
Мой друг живёт на третьем этаже.
My friend lives on the third floor.
In this example, 'третьей' is also an ordinal number 'third', but in the instrumental case, describing the position of the 'page' in the book.
На третьей странице книги была иллюстрация.
On the third page of the book, there was an illustration.
Here, 'третье' specifies 'third' as an ordinal number and is in the nominative neuter case, matching the noun 'место' (place).