Question

Europe is rightly called the ‘peninsula of peninsulas’.

Answer 1

Europe is sometimes called a "peninsula of peninsulas", to draw attention to the fact that Europe is a relatively small, elongated appendage to Asia, and that a large part of Europe is made up of peninsulas.

Answer 2

Only one side of the continent is connected with other continent and all other side is surrounded by water. In the west, they are surrounded by the Atlantic Ocean. South is Mediterranean Sea and North is Arctic Ocean. There are also peninsula in Europe like Italy, the Spain-Portugal, and the Scandinavian (Norway, Sweden, Denmark, and Finland), and I think that is why those are called peninsula of the peninsula.