i want to learn about football

Ball in other teams net, yay!
Ball in own teams net, boo!
Some one bumps you, fall over and cry like a baby.

This is the extent of my knowledge.

.... just say 'weren't they offside' when a goal is scored and theres a lot of players near the goal. Oh ask your BF to explain the offside rule... have fun.

It's 22 people on a pitch running around and trying to kick a ball into nets between posts.

"football made simple"

I guess this will help you to understand and even to teach him

The aim of the game is to score more goals than the opposition, which is done by kicking the ball into their goal, whilst also defending your own. A player can pass the ball to anyone else on the field, and unlike some sports, is allowed to run with the ball. There are only a few rules to abide by when it comes to passing. The first is the offside rule, which we’ll come to later. The next one is when passing back the goalkeeper. If you pass the ball to your keeper using your feet, he must play with his feet too. If you head the ball back to him, then he is allowed to pick it up.

Quickfire rules

The ball is kicked off from the centre spot at the start of each half and after a team scores. Up until recently, you had to initially pass the ball forwards before passing it backwards, but it is no longer the case.
No players can be in the opposition half when kick-off occurs.
Any foul can result in a free kick, or a penalty if the foul takes place in the penalty area. There can be free-kicks in the area as well under the right circumstance.
If the attacking team kicks the ball beyond the goal line, this results in a goal kick. If the defending team kicks it behind their own line, the attackers are awarded a corner kick.