Just try to explain the concept of unblocking to a football player. Lots of luck! It’s a good practice in bridge. Here’s a standard definition: “Unblocking is the process of playing a higher card to establish enough entries to make the necessary tricks. It sometimes can involve playing a high card in one hand so tricks can be taken in the other hand.” — Google.

Here’s an example of how unblocking works — or doesn’t work. I was sitting East and dealing on an OK Bridge Internet hand, with North-South vulnerable:

                         NORTH
                        ♠️ K 10 9 3
                        ♥️ 7
                        ♦️ 9 6
                        ♣️ A Q 8 6 5 2

    WEST                                       EAST
    ♠️ 8 7 5                                  ♠️ A J 6 2
    ♥️ A10 9 8 5                          ♥️ K J 4 3 
    ♦️ Q 5 4                                 ♦️ J 3 2
    ♣️ K 9                                    ♣️ 10 7

                      SOUTH
                     ♠️ Q 4
                     ♥️ Q 6 2
                     ♦️ A K 10 8 7
                     ♣️ J 4 3

    The bidding proceeded as follows:

    East            South        West        North
    Pass            1♦️          1♥️        DBL•
    2♦️••         Pass          2♥️        3♣️
    Pass            3NT        All Pass

    • Shows at least four spades

    • • Limit raise in hearts

    Opening lead: ♥️10

    I won the opening lead with the ♥️K and returned the ♥️3 to the ♥️9. Now partner cashed the ♥️A, dropping the ♥️Q, and led the ♥️5 to my ♥️J. Whoops! We never cashed the fifth heart.
    Knowing partner had five hearts to my four, I should have unblocked with the ♥️J on Trick Two. Now, whether or not declarer puts up the ♥️Q, the suit can run out smoothly.

    By the way, beware of bidding 3NT with queen-third in a suit both opponents have bid.