"Il y a” in French — Different Uses

"il y a" to say there is or there are in a place or situation.

Il y a un chat dans la maison.
There is a cat in the house.

Il y a trois étudiants dans la classe.
There are three students in the classroom.

"il y a" before a length of time to mean ago.

Je suis arrivé il y a 10 minutes.
I arrived 10 minutes ago.

Il a mangé il y a deux heures.
He ate two hours ago.

In the past, with imparfait or passé composé.

Il y avait un chien ici.
There was a dog here.

Il y a eu un accident.
There was an accident.