noun
countable; finite number
Used in mathematics to describe a set or collection that has a finite number of elements. Often contrasted with 無限個 (infinitely many).
この集合は有限個の要素からなる。
This set consists of a finite number of elements.
有限個の例外を除いて、すべての自然数はその性質を持つ
All natural numbers have that property except for a finite number of exceptions.
有限 is a broader adjective/noun meaning 'finite' or 'limited', while 有限個 specifically refers to a finite number of countable items.
Compound of 有限 (finite) and 個 (counter for individual items), literally 'finite pieces'. A straightforward technical term.