It’s fine! So the UK voted out, but the difference between the remain and leave votes was only about 3%. Because the turnout of the entire referendum was 72%, and leave only won by this 3% people want a revote - as it seems kinda unfair! This is apparently set to start in October, when our Prime Minister (David Cameron) is set to step down from power. 
I think the main issue is the GBP has lowered by 8%, dropping it’s value the most ever in 31 years. (dropped from 1.5 to 1.3) - which may affect the dollar? I’m not totally sure.
But if American companies are situated in London, then jobs and estates are likely to be moved to Dublin and Frankfurt as not to disturb relationships with the EU. 
I guess additionally, Britain is seen as a sort of gateway for the US to get free or minimal expense trades to other EU countries, however this Brexit now means that the access to these markets have been disrupted which may reduce profits.

It’s really just a waiting game at this point! Really to summarise it’s just gonna affect people financially, beit by big or small amounts!