This is the 397th most frequent Hungarian word.
mellé
"Next to" or "beside" (indicating movement to a position next to something).
In this sentence, 'mellé' indicates the placement of the book to the location beside the table, describing spatial relation.
A könyvet az asztal mellé tettem.
I placed the book next to the table.
Here, 'mellé' specifies that the picture was hung next to the wall, denoting adjacency.
A képet a fal mellé akasztotta.
He hung the picture beside the wall.
In this case, 'mellé' describes sitting next to someone, expressing proximity in position.