These are fuses for the electrical system of a house. Most homes that you see these days have been updated to circuit breakers, so finding fuse boxes becomes less common each year. It’s okay to want to buy a house that has fuses, but you should plan for them to be upgraded. Perhaps you’ll be able to convince the seller to deal with them before the closing. That’s unfortunately not always possible though, so just make a mental note as you’re evaluating the property.