Learn Russian: Я был здесь один раз.

In Russian, there isn't a single word that exactly matches the English word "once." Instead, you say один раз, which literally means "one time." The word раз means "time" in the sense of an occurrence or instance.

Does the verb был change if a woman is speaking?

Yes! In the Russian past tense, verbs must match the gender of the subject. Because был ends in a consonant, we know a male speaker is saying this sentence. A female speaker would add an -а to the verb and say, Я была здесь один раз.

Why isn't the word for "time" here время?

Russian has two different words for "time." You use время when talking about time in general or time on a clock. You use раз when you are counting how many times something happens, like "one time" (один раз) or "every time" (каждый раз).

Could I put the time expression at the beginning of the sentence?

Yes, Russian word order is very flexible. Saying Один раз я был здесь is perfectly correct. Moving the time expression to the front just puts a little more emphasis on the fact that it happened exactly one time.