Learn Hardcore Russian: Я понял правило.

In Russian, only the first word of a sentence is capitalized. Unlike English, the pronoun я (I) does not get a capital letter every time it appears—here it’s Я simply because it starts the sentence.

What case is правило in, and why doesn’t it change its ending?

Правило is the direct object of the verb понял, so it’s in the accusative case. Since правило is a neuter noun, its accusative singular form is identical to the nominative singular (правило), which is why you don’t see any visible change.

What does the ending -л in понял indicate?

The -л ending marks the past tense, masculine singular of the perfective verb понять (to understand). In Russian past forms, verbs agree in gender and number—not person—so понял means “I (male) understood” or “he understood.”

How would this sentence change if a woman said it?

A female speaker would use the feminine past ending -ла: Я поняла правило. Only the verb form changes gender; the noun правило remains neuter. For “we understood,” you’d say Мы поняли правило (plural past).

What’s the difference between понял and понимал?

понял is from the perfective verb понять, indicating a completed action: “I understood (it completely).”
понимал is the past tense of the imperfective verb понимать, indicating an ongoing or habitual action: “I was understanding,” “I used to understand,” or in context “I didn’t understand … for a while” (e.g. Я долго не понимал правило).

Could I drop the pronoun я and just say Понял правило?

Yes. Russian often omits the subject pronoun when it’s clear from context. In speech, Понял правило is understood as “I understood the rule.” Note that in the past tense, the verb only shows gender and number, so you lose the explicit “I,” but usually it’s still clear.

Why is there no word for “the” before правило?

Russian has no articles (no “a” or “the”). Definiteness is inferred from context. So Я понял правило can mean “I understood the rule” or “I understood a rule,” and your listener uses the situation to know which.

How do you ask “Did you understand the rule?” in Russian?

Informal singular: Ты понял правило? (to a male) or Ты поняла правило? (to a female).
Formal or plural: Вы поняли правило?.
Just add a question intonation (or a question mark in writing); the verb changes for gender in singular and adds -и in the plural/formal form.