In sports cards, PC means ‘Personal Collection’.
You will often hear card collectors say, “I PC Ken Griffey Jr. and Bo Jackson.”
But just as commonly, you might hear, “I collect Ken Griffey Jr. and Bo Jackson for my PC.” Or, “These cards are part of my PC and are not for sale.”
Its also common for sports card collectors to list the players and/or types of cards (game worn patch cards, autographs, non-sports cards, etc.) they collect on their social media profiles, using the PC acronym. For example:
PC: Brady, Mahomes, Goff, any vintage HOF
In short, its just a quick way to help describe what you collect!