Okay kiddo, so imagine that you live in a house that is surrounded by other houses and you can only get out by crossing your neighbors' yards. But let's say that your neighbors decide to lock their gates and not let you pass through. That would be really unfair, right? Well, this is kind of what can happen to a country that doesn't have access to any ports because it's surrounded by other countries.
That's where the convention on transit trade of land-locked states comes in. It's a big agreement that lots of countries made to help make sure that landlocked countries can still trade with other countries even if they don't have a coast. The convention says that all the countries that are around the landlocked state have to give it safe and easy access to stuff like ports, highways, railways and airports.
This way, the landlocked country can still trade with other countries and get all different kinds of things that they might need or want like food, medicine, and toys. It helps them stay connected to the rest of the world and not get cut off just because they don't have a coastline. It's like making sure that all the neighbors around your house leave a gate open so you can still play with your friends and go on adventures.