Which of these tasks does an executor do when settleing an estate?

Well, you didn't give us a list of the possible tasks to choose from, but The basic duties of an executor are:

Find a copy of the latest will, if any;

Find all of the assets of the deceased (real estate, personal property such as cars, art, and antiques, bank accounts, brokerage accounts, and other investments, loans made by the deceased to others, etc.);

Find all of the debts and Accounts Payable by the deceased;

Find out if probate court proceedings are necessary, and file the will, if any.

Notify anyone who should know of the deceased's passing, including not only individuals but also government agencies such as the Social Security Administration and DMV, banks, and brokers.

Unless the will describes specifically how to deal with assets, decide how to deal with them in a way that will preserve their value and enable their distribution (for example, should a house be sold, or rented, or left empty? Should stocks and bonds and other investments be sold or held? Should antiques be sold at auction and by whom?);

Set up a bank account in the name of the estate, using money available from the estate and any income that comes in while the estate is being settled (however, large amounts of income should probably be invested in one of the safe investments permitted by state law);

Use the bank account to pay ordinary bills and make mortgage and other loan payments;

Terminating services or accounts that are no longer necessary, such as credit accounts, subscriptions (including internet subscriptions), leases, and services like phone and internet: services;

Pay all debts owed by the deceased;

Pay taxes and if necessary file a tax return for the estate; and

Distribute what's left in the way specified in the will or if there's no will, according to state law.