OK, so imagine you have a toy car. You play with it and take care of it, but your parent or guardian is the person who actually bought the car and owns it. They are the "haltija" of the car, which means they are the legal owner of it.
So, a "haltija" is basically someone who legally owns something, like a car or a house. Even if you use or take care of it, the haltija is the person who has the legal right to say what happens to it. It's like if you borrow a toy from a friend - you can play with it, but your friend is still the owner and gets to decide if you have to give it back or not.
In some cases, the haltija might give you permission to do certain things with what they own. For example, your parent might let you drive their car when you're old enough and have a license. But ultimately, it's up to the haltija to decide what happens to their property.