"I would like two hundred and fifty grams of potatoes."
Let's break it down:
* Je voudrais: This is the polite way to say "I would like" in French.
* deux-cent cinquante: This means "two hundred and fifty".
* grammes: This is the plural form of "gram", a unit of weight.
* de pommes terre: This means "of potatoes".
So, the whole phrase expresses a request for a specific amount of potatoes.