Unfortunately, that means the item has not been delivered.
If only a few days have passed since posting, the item may still arrive. Bad weather around the country has delayed some deliveries.
When this has happened to me I've sent the buyer a message apologising for the delay, but asking them if they would kindly wait another few days, as bad weather could be a factor here delaying their item. Assure them their money is safe, if it doesn't arrive say by mid next week, you will fully refund them as per the rules of eBay's MBG, Money Back Guarantee policy.
If the item remains undelivered, the buyer should open a case for item not received, with no tracking to show delivery, fully refund through those case details.
After the item has been missing 10 days , put in a claim with Royal Mail for compensation for yourself, for a lost parcel.
@sal-71312