Suspense Account

Can someone explain the following question?

One more question:
Your organisation’s trial balance at 31 October 20X9 is out of agreement, with the debit side totalling $500
less than the credit side. During November, the following errors are discovered:
???? The sales journal for October had been undercast by $150
???? Rent received of $240 had been credited to the rent payable account
???? The allowance for receivables, which decreased by $420, had been recorded in the allowance for
receivables account as an increase
Following the correction of these errors, what is the balance on the suspense account?
$ debit/credit (delete as appropriate)

I did not understand 1st error. Does that error need to be corrected?
Thanks
🙂