What does it mean when a p-value is called the minimum significance level?

It means the p-value is the rejection threshold expressed as an alpha level.

If a test has p-value = 0.023, then the test rejects the null for any alpha of 2.3% or higher. It fails to reject for any alpha below 2.3%.

That definition is useful when answer choices list several significance levels. Suppose a question asks at which significance levels a result with p-value = 0.023 is significant:

• At 10%: reject.
• At 5%: reject.
• At 1%: fail to reject.

The result is statistically significant at 10% and 5%, but not at 1%. The p-value does not change. The chosen Type I error tolerance changes.