na-adjective, noun which may take the genitive case particle 'no', noun
a great variety of; diverse; wide-ranging
Emphasizes both numerous kinds and diversity. Used as a な-adjective, の-adjective, or noun. Common in formal and written contexts.
この店には多種多様な商品が並んでいる。
This shop has a great variety of products on display.
多種多様の意見
A wide range of opinions were expressed.
多種 means 'many kinds'; 多種多様 combines this with 多様 to stress diversity as well.
A yojijukugo composed of 多種 (many kinds) and 多様 (diverse). The exact historical derivation is uncertain, but it follows a common pattern of combining two two-character compounds to form a four-character idiom.