Your real cash balance is what the bank says you have, read directly from the bank connection.
It is shown separately from the balance in your books because the two answer different questions and frequently disagree.
Why they differ
Your books know about a payment when it is recorded. The bank knows about it when it clears. Between those two moments the same business has two different balances, and both are correct.
Cheques not yet presented, card payments still settling, and transfers in flight all live in that gap. Anything entered in your books but not yet at the bank widens it.
Which one to trust
For "can I make payroll on Friday" — the bank. It is the money that exists.
For "did we account for everything" — the books, checked against the bank. That is reconciliation.
The gap itself is worth watching. See the variance between your books and your bank.
The trap
A real cash balance that looks healthy is not the same as money you can spend. Payroll, tax and the bills already committed all still have to come out of it, and none of them are visible in the balance.
The balance tells you what is there. Cash runway tells you how long it lasts.