Learn Spanish (Spain): Ayer, la mujer se quedó muda con la noticia. - Yesterday, the woman was left speechless by the news.

The verb quedarse followed by an adjective is a verb of change. It doesn't just mean she "was" speechless; it means she became or was left speechless as a direct result of an event. We use it to focus on the new state caused by the news.

Why is the word for speechless muda instead of mudo?

Because muda is an adjective describing la mujer (the woman). Even though it's part of the set expression quedarse mudo, the adjective must still match the gender and number of the person experiencing the change.

The translation says "by the news," but the Spanish uses con. Why not por?

When talking about a reaction to a specific trigger (like a surprise, a joke, or a sudden event), Spanish often uses con (literally "with"). You can think of it as her being left speechless "upon receiving" or "with" the news.

Why is la noticia singular when the English translation says "the news"?

In English, "news" is an uncountable noun. In Spanish, noticia is countable. La noticia refers to a single, specific piece of news. If she were reacting to a whole news broadcast or multiple stories, you would use the plural, las noticias.