The limit is the maximum amount you can overdraw from the bank. In case of overdraft, it is generally 1/5.

The accounting period is interest-free time. From the bookkeeping date, the bank tells you how many days the accounting period is at most. In other words, if you start spending from the second day of the accounting day, then your accounting period is so many days. If you spend money on the day of bookkeeping, your interest-free period is generally only ten or twenty days.