What exactly does the term Talisman meaning in football/soccer? A talisman is something or someone who produces apparently magical or miraculous effects.
In soccer, the talisman is a key figure on the soccer team who just adds that extra special something, whether it's scoring big goals or a defender who's always there at the right place and time to block a shot or make that game saving tackle. So when that player isn't available the team really suffers.
The talisman can also be someone who comes off the bench late in the game. These days, for Manchester United, Jesse Lingard is an example of a talisman for his club team. Whenever he's on the soccer field at the start or comes off the bench good things happen. In fact, he's been scoring some great goals for Manchester United this year.
Often you'll hear TV announcers refer to a football/soccer player as the team's talisman. Think Ronadlinho when he played for Barcelona or Henry when he was with Arsenal. With that particular player the team can win, without that player they will often lose or struggle to play well, that's what a talisman is.
In the end a talisman is that thing or player that makes a team successful and play well. For Barcelona I'd say their talisman is Andres Iniesta. He just makes the team run. Often every pass goes through him. When Iniesta isn't in the side they have to change their style of play to an extent and look to go through another player.