Herbata staje się zimna.

The tea is becoming cold.

Breakdown of Herbata staje się zimna.

• herbata: the tea
• zimny: cold
• stawać się: to become

Questions & Answers about Herbata staje się zimna.

What does staje się mean and how is it different from jest?

Staje się is the 3rd-person-singular present form of the imperfective reflexive verb stawać się, meaning to become. It highlights an ongoing change – roughly “is becoming” – whereas jest simply states a static fact or condition, “is,” with no sense of process.

What is the role of się in staje się?

Się is the reflexive pronoun that makes stawać się a single lexical unit meaning to become. It is an enclitic, so it must follow the verb (you cannot say się staje or insert anything between staje and się).

Why do we use zimna here instead of zimno?

Zimna is the feminine singular form of the adjective zimny, agreeing with herbata (a feminine noun) in the nominative case. Zimno by itself functions as an indeclinable adverb or impersonal predicate (“it’s cold”) and does not agree in gender.

Shouldn’t the adjective after staje się be in the instrumental case (i.e. zimną)?

Traditionally, verbs like stać się govern the instrumental (for example stał się bohaterem). In very formal or prescriptive grammar you might see Herbata staje się zimną. In modern usage, however, adjectives after staje się are almost always in the nominative, so zimna is far more common and perfectly acceptable in everyday speech.

What is the aspect of staje się, and is there a perfective counterpart?

Staje się is imperfective, describing the process of becoming cold. The perfective counterpart is stać się, so if you want to say “The tea became cold” as a completed action, you’d use Herbata stała się zimna.

Could we use other verbs like robi się, ostyga, or schładza się to express the same idea?

Yes.

• Herbata robi się zimna is almost synonymous with staje się, just a bit more colloquial.
• Herbata ostyga or Herbata się ochładza are the most natural everyday ways to say “the tea is cooling down.”
  Staje się tends to sound more literary or formal.

Where is the stress in the sentence Herbata staje się zimna?

Polish words are stressed on the penultimate syllable. The pronunciation pattern is:
her-BA-ta STA-je się ZIM-na
with the main word stresses on BA, STA, and ZIM.

Why isn’t there an article before herbata like in English “the tea”?

Polish does not have definite or indefinite articles. A bare noun like herbata can mean “tea,” “the tea,” or “that tea” depending on context. If you need to specify “that tea,” you could say ta herbata.