たくさん　あります or　たくさんが　あります?
I have seen the sentence in my book as follows:
べっそうも　たくさん　あります。
but as I have learned the pattern -があります, so I wonder why it isn't
べっそうも　たくさんが　あります。Can anybody helps me with that？

Question

たくさん　あります or　たくさんが　あります?
I have seen the sentence in my book as follows:
べっそうも　たくさん　あります。
but as I have learned the pattern   -があります,  so I wonder why it isn't 
べっそうも　たくさんが　あります。Can anybody helps me with that？

Answer

べっそうがあります　There are Japanese hostels.
べっそうがたくさんあります　There are many Japanese hotels.
べっそうもあります　There are also Japanese hotels.
べっそうもたくさんあります There are also many Japanese hotels.

When you say 〜があります、〜 part should come Noun. Not adjective, not adverb. 
べっそう is Noun.

Answer

se dice hay muchos afirmando la oracion y hay muchos? es una forma de preguntar

Não perca a oportunidade de aprender uma língua no conforto da sua casa. Navegue pela nossa seleção de professores de línguas experientes e inscreva-se na sua primeira aula agora mesmo!