Translation:There are a number of people eating in that restaurant.
"A number of people" is singular so it should be "There is a number of people ..."
I disagree. How many people are there? Are there five? Are there ten? Well, no, there are a certain number of people, though I do not know what the exact number is. I would suggest this use of singular and plural verbs.
I think this may come down to whether you speak a British, US or another variety of English. Personally "Are a number" works better for me in Australia.
This blog posts says both are correct https://www.grammarly.com/blog/there-is-there-are/
Whereas the oxford dictionary says "There Are" is the correct way https://en.oxforddictionaries.com/explore/number-of-people-is-or-are/