Thought it was pretty obvious, but anyway here is a wiki explanation for you : https://en.wikipedia.org/wiki/Marquee_player
I realise its not our business plan to buy them, but would be nice to have a top class player in our 11, even if slightly on the decline. Worked well for us in 83/84..good combination of youth and experience.
Anyway, back to reality Rashica who was linked with us before is now lined up as Sancho replacement at Dortmund : https://www.telegraph.co.uk/football/2020/07/22/manchester-uniteds-hopes-signing-jadon-sancho-boosted-dortmund/