This is the 88th most frequent Portuguese word.
este
"Este" means "this" in English.
In this sentence, 'este' is used as a demonstrative adjective to specify that the book being referred to is near the speaker.
Este livro é muito interessante.
This book is very interesting.
Here, 'este' serves as a demonstrative pronoun, directly referring to the subject being introduced, my brother.
Este é meu irmão João.
This is my brother John.
In this case, 'este' functions as a demonstrative adjective to denote a problem that is specific and pertinent at the moment being addressed.