noun
commentator; explainer
A person who provides commentary or explanation, such as a sports commentator, news analyst, or someone who explains a topic.
彼はテレビのスポーツ解説者として有名だ。
He is famous as a TV sports commentator.
この本の解説者は著名な学者です。
The commentator for this book is a renowned scholar.
Means 'explainer' or 'person who explains'. 解説者 implies a more expert or analytical commentary, while 説明者 is simply someone who gives an explanation.
Compound of 解説 (explanation, commentary) + 者 (person). The reading is standard on'yomi.