This setting defines the maximum number of orders allowed for one symbol on the Receiver account, if the number of orders on this account for this symbol is more or equal to this parameter then all new tasks from the Source will be ignored. 
So for example:

1. You set "Ignore new orders for symbol if current number of orders for this symbol is..." = 2.
2. Currently there are 2 BUY EURUSD orders and 2 BUY STOP GBPUSD orders on Receiver account.
3. After that you get the new task from the Source (let's say SELL USDJPY order). This order will be processed, so you will have 2 EURUSD orders + 2 GBPUSD orders + 1 USDJPY order.
4. After that you get another task from the Source (let's say BUY STOP EURUSD order) this task will NOT be processed because the total number of orders for EURUSD = 2.

 To activate this setting please open Forex Copier 2 program, click “Settings” on Receiver account, go to “Filtering orders” tab, activate “Ignore some orders from Source account”, click “Show advanced settings”, activate “Ignore new orders for symbol if current number of orders for this symbol is … or more” and enter necessary value there.
After this, please click “Save and Finish” button and then “Apply Scheme” to apply new settings.