Please help me to find synonyms for the word festival in english,or other words related to that.Thank you in advance.

What you are looking for are synonyms (words that mean the same as) for Festival.

Here are some in English:
Festival Synonyms, Festival Antonyms | Thesaurus.com

The closest to the basic word "Festival", in my opinion, would be

Carnival
Fair
Festivity
Fiesta
Gala
Jubilee