Every statement begins with an opening balance. It is simply the amount you owed at the start of that statement period — the launch point from which every payment and charge on the statement moves the figure.
Where it comes from
The opening balance is carried straight over from the closing balance of the previous statement. That is why consecutive statements should always tie together: last period's closing figure is this period's opening figure. See opening and closing balance defined.
Following it through the period
From the opening balance, each repayment reduces it and each charge adds to it, ending at the closing balance. See reading the running balance and the transaction list explained.
If it does not match
If a statement's opening balance does not equal the previous statement's closing balance, something is off — query it. See I think there is an error on my statement and how to check a statement line you don't recognise.
Credicorp lends to companies rather than to you personally, so this is business finance outside the consumer-credit regime. That does not change the practical steps below.
See also: Opening and closing balance (definition), Reading the running balance, The summary panel at the top of your statement.