Could someone explain to me accured expenses and revenue?

Accrured Expenses are the expenses in respect of which the liability has been already incurred but liability is not settled or paid or either postponed for some other period due to some reasons. Example. Salary to employee is payable on 30th of each month (say march), however, the payment of salary will be made on 10th of next month (say april). Hence, the salary payable to employee will accrue on the month concerned i.e.March, which should be booked in the same month in order to access the performance of the organization in concerned month.

Accrued Incomes are the incomes, in respect of which the right to receive the income is due but not received at the time of closing of accounts. As rental income of business complex for March is due on 31st March, but rental income will be received on 15th of April. Hence, in the monthly closing of books of accounts, the rental income of business complex is required to show, but still not received. Hence, the income will be accounted under Accrued Income.
Entry Will Be:
Debit: Accrued Income
Credit: Income from letting of property

On receipt of Rental Amount:
Debit: Bank Account
Credit: Accrued Income

Please note: Accrued Expenses is Short Term Liabilities and Accrued Income is Receivables, which will appear in Balance Sheet.