It's claiming that there are sequences on the viral code that are unlikely to have occurred naturally, but are really convenient for slicing the genetic sequence in a lab context.
Sort of like if you shaved the fur on a hyena and discovered a "THIS END UP" tattoo on its skin.
Or rather: you have many hyenas without fur, and on the skin you can see scars that suggest the skin has been cut at very specific places, places where you'd normally see operation scars. Now all the discussion has come down to is how likely it is that the positional patterns and the type of scar itself could occur in nature. For example whether Hyena bites and scratches make the same scars as human scalpel.
On October 18, these three scientists presented an argument with evidence that Covid-19 was created in a laboratory. Their paper has not been peer reviewed, and it is self-published. The discussion here has a couple of counter-arguments. Non-experts would do well to wait for peer review before accepting these arguments.
Sort of like if you shaved the fur on a hyena and discovered a "THIS END UP" tattoo on its skin.