入場時間って英語でなんて言うの？

If you want to ask when the entry for a venue closes, you can ask:
What time do the gates close?
The gates in this sense refer to the walls or door that would prevent someone entering.

In some places it can also be:
The last call
When is the last call?

I hope that helps!

1. To get in = to enter a place such as a shop, restaurant, cinema, theatre or other venue
   "My son tried to get into an adult movie but was too young.." = He wanted to enter a cinema to see a film.
2. To gain entry = To be successful in entering a venue.
   "I've been trying to gain entry to the restaurant for 20 minutes, but the queue isn't moving."
3. To let (someone) in = admit someone to a room, building, or area.
   "I had to wake up my flatmate Veronica to let me in."

"What time does admission end?"
admission = entry into a building,park event venue

"When do you shut down?"
This is a casual way of asking when the venue closes.

"Until when will I be allowed to enter?"
This is another way to ask what the time restrictions are for entry/re-entry.

Most venues have a cut off point for the time of the last possible entry/admission.
This is of course the admission time deadline...
"Can you tell when the admission time ends please?"

All these are suitable ways of saying the last possible time for getting into the venue.
Admission means to gain entry or to go into somewhere so you would say the admission time of the venue was from 10am to 4pm.
The last time means that it is the last time you will be allowed to get into somewhere before it closes.

When you want to ask about the time for the last entry into a venue, then you can ask in the following ways:
-what time is the last round of people to go in?
-what time are you letting the last round of people in?