voilà v. il y a

Il y a and voilà are two ways of introducing nouns. They are translated into English as 'there is / there are' or 'here is / here are.'

il y a

Il y a + noun usually indicates the existence of a person or a thing in the context of a particular setting. It is commonly translated as 'there is' or 'there are.' For example:

 The negation of 'il y a' is il n'y a pas, 'there is / are not'. You will also find these forms:

il n'y a plus, 'there is / are not anymore', 

il n'y a jamais, 'there is / are never'.

The verb avoir in the expression il y a may be conjugated in any tense or mood, for example, in the past (il y avait , 'there was') or in the future (il y aura, 'there will be.')

voilà / voici

Voilà + noun and voici + noun are commonly translated as 'here is/are'. They are used to indicate  the sudden appearance of something or someone, to introduce people or ideas. Alternating between voici and voilà is common when referring to more than one item.