"The spider falls off the wet window."
Translation:A pók leesik a vizes ablakról.
Welcome to the many weirdness of the hungarian language. The "le" prefix can mean "down" or "off". For example, a sticker can fall off from a book (doesn't necessary mean it falls towards the ground, it means only the adhesive solution is not working anymore). In this case poor spider has lost its ability to stay on the surface of the window, but we are not sure (yet) if its ass-rope will save it from falling down or not. - or this can be a really general statement like "well, if Spidey tries to walk on the wet window (in any moment in the present or in the future), it won't be successful due to the decreased traction".
In hungarian "Esik az eső" means "it's raining (now)", whereas if you say "Holnap leesik az eső", that means "it will start to rain tomorrow". It also can be used in past tense "Leesett az eső", in that case instead of the usual "Esett az eső / It was raining" it implies that "(after a long while) it started raining (again).
"Esik" (without any prefixes) can be also used for blood pressure or other levels and measurements (the numbers are dropping) - in these meaning the only prefix you can use is "le".
In everyday use you also can say "beesik" (someone has JUST arrived in a hurry - or the throwed object land inside a container object), "kiesik" (fall out from a container), "felesik" (not that widely used although grammatically correct, e.g: when you are walking, tripped and fell, and the landing area is higher than the surface you were previously on - or a kid is thowing a ball upwards but at some point it stucks on a tree). Not to mention "bele", "ide", "oda" :)
As you can see, in 90% of the cases the prefix must be used.