This is the 2520th most frequent Russian word.
размера
The Russian word "размера" means "of size" or "size" in the genitive singular form.
In this sentence, "размера" is used in the expression "небольшого размера" to describe the size of the book, literally meaning "of small size."
Эта книга небольшого размера, удобно носить с собой.
This book is small-sized, convenient to carry around.
Here, "размера" appears in the phrase "такого размера," indicating a specific or given size of an object, in this case, a car.
Машина такого размера не подойдет для нашего гаража.
A car of this size will not fit in our garage.
In this example, "размера" is part of the combination "разного размера," which emphasizes diversity in the sizes of the boxes.