Foot fetishism is when someone gets very excited or turned on by feet. It means they really like feet and want to look at them, touch them, smell them, or sometimes even lick them. It can be like how some people like ice cream, but instead of ice cream, they like feet.
Just like how some people feel excited when they see someone they find attractive, a person with a foot fetish may feel excited when they see someone's feet that they find attractive. It's important to remember that having a foot fetish is perfectly normal and ok, as long as it is consensual and respectful to everyone involved.