Use the preposition 'under' to talk about people/things/animals that are below something:
The bench is under the tree.
The cat is under the book.
The dog is under the table.
Use the preposition 'over' to talk about people/things/animals that are above something, or covering something:
The tree branches are over the bench.
The boy is over the hurdle.
The laptop is over the boy's head.
Use the preposition 'in front of' to talk about people/things/animals that are further ahead than someone/something else:
The door is in front of the girl.
The phone is in front of the people.
The man is in front of the women.
Use the preposition behind to talk about people/things/animals that are at the back of something/someone:
The girl is behind the door.
The girl is behind the tree.
Use the preposition 'between' to talk about things that are in the middle of two other things.
The girl is between her parents.
The bridge is between the buildings.
The dog is between the couple.
'Over' means there is some space between the two things. 'On' means that the two things touch. You can say "There is a plane over us" but you cannot say "There is a plane on you."
