We use a lot of with both countable and uncountable nouns in the affirmative.

Analysis of the sentence:

• This sentence states the usage of the phrase 'a lot of'.
• 'A lot of' can be used with both countable and uncountable nouns.
• It is primarily used in affirmative statements.

Explanation: This rule introduces 'a lot of' as a versatile quantifier that works in affirmative sentences for both types of nouns.