I'm not a soccer fan...so I won't be going out of my way to watch any of the World Cup games. Part of the reason I skip it is because I don't "understand" all the terms.
If you want to watch without feeling "stupid" or "clueless"...then check this out. According to Elite Daily, here's your WORLD CUP DICTIONARY (in alphabetical order):
1. Advantage: A referee “plays” advantage when a player fouls a member of a team with the ball, but the ref decides not to call the foul in order to let the team continue with advantageous progression of play.
2. Back line: The defensive unit of a team.
3. Boot: Cleat.
4. Booking: The act of a player receiving a yellow card, usually for a serious foul.
5. Byline: Denotes the lining between a goalpost and a corner flag. Analogous to the “baseline” in basketball.
6. Cap: Refers to the amount of in-game appearances a player has made for his national side.
7. Challenge: An attempt to win possession of a ball, whether it be aerially, or via a tackle.
8. Clearance: Describes the act of a defender kicking a ball clear from danger and members of the opposition who are in an offensively advantageous position.
9. Custodian: A term sometimes used to describe a goalkeeper.