Entry or admission: entering a venue or the right to enter (e.g., with a ticket).
チケットがあれば入場できます。
You can enter if you have a ticket.
開場は18時、入場は19時からです。
Doors open at 6:00 PM; admission starts at 7:00 PM.
火災報知器が鳴ったため全員入場を停止した（＝退場を促した）。
Because the fire alarm went off, entry was stopped for everyone (i.e., people were urged to exit).