Entity page and customer account

when you click the customer account and you select the customer account the balance of the customer shows on the screen like the above picture ,
I saw this on another system and will love to implement it on my system

I don’t understand - the “other system” you saw it on clearly has your name as the customer, and it also clearly shows the balance. So I believe you have this “other system” already? This is also automatic once you have created an account for the customer.

the other system in not mine it for another shop

Balance shows up by default if there was something previously put on the customer account. Does it not show on yours?

i had a problem with the customer account setup
but now it fixed
thank you