"Will listen to offers" means desperately attempt to sell in this context.
I think clubs will offer loans or only poverty bids for all these players except Kovacic.
Nobody is taking Koulibaly and his contract at age 32, maybe a loan where Chelsea partially subsidizes the wages.
Ziyech and Pulisic both have the issue of failing in the PL and needing to be sold abroad, where nobody has money and the few clubs with money will want a higher ceiling solution. Loans or very cheap deals.
Auba will get no interest at all and you'll have to pay him off to leave via contract termination.
CHO is still young and English, so a club like Forest might buy him, but whether he'd be willing to take that kind of step down I don't know.