The second use of haber is to express existence. haber = there is or there are. It’s impersonal, invariable and it doesn’t reflect gender, person or number.
Present tense hay = there is (are)
Preterite tense hubo = there was (were)
Past (Imperfect) tense había = there was (were)
Future tense habrá = there will be
Present Condicional habría = there would be
Present Perfect ha habido = there has (have) been
Past Perfect había habido = there has been
Examples:
¿Qué hay en la clase? What is in the classroom?
En la clase hay muchos libros. In the classroom, there are many books.
¿Cuántas bibliotecas hay en la escuela? How many libraries are there in the school?
Hay una biblioteca en la escuela. There is one library in the school.
Hay muchos estudiantes ausentes hoy. There are many students absent today.
Hubo mucha gente allí. There were a lot of people there.
Había siempre tres páginas en sus cartas. There was always three pages in his letters.
Sentences
Hay miles de fanáticos de la estrella de cine. There are thousands of movie star fans.
Hay niños con hambre en todo el mundo. There are hungry children in all the world.
Hay una silla en la cocina. There is a chair in the kitchen.
Hubo un millar de aficionados. There are a thousand enthusiasts.
Hubo niños que no fueron a la fiesta. There were kids that didn't go to the party.
Hubo un sofá viejo en esa sala. There was an old sofa in that room.
Había un piano en el salón. There used to be a piano in the living room.
Había cinco pacientes esperando al doctor. There were five patients awaiting the doctor.
Había veinte escritorios en patio. There used to be twenty desks on the patio.
Habrá comida para todos. There will be food for everyone.
Habrá cientos de premios. There will be hundreds of prizes.
Habrá una multitud de gente en el concierto. There will be a multitude of people at the concert.
Habría más o menos cincuenta espectadores. There would be more or less fifty spectators.
Ha habido mucha controversia sobre la muerte del cantante. There has been a lot of controversy about the death of the singer.
Ha habido miles de cartas de los fanáticos. There have been thousands of fan letters.
Ha habido cientos de llamadas teléfonicas al congreso. There have been hundreds of telephone calls to congress.
Había habido muchos muchachos interesados en el proyecto. There have been many guys interested in the project.
Había habido un pasado muy oscuro. There has been a very dark past.
