Я купил новый шампунь.

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Breakdown of Я купил новый шампунь.

• купить: to buy
• новый: new
• шампунь: the shampoo

Questions & Answers about Я купил новый шампунь.

Why is there no article before новый шампунь like “a” or “the”?

Russian does not use articles. Context, word order, or extra words (e.g. какой-то шампунь for “some shampoo”) convey definiteness or indefiniteness, instead of “a” or “the.”

What exactly does купил mean, and why this form?

купил is the past tense (1st person singular) of the perfective verb купить (“to buy”). The perfective aspect indicates a completed action (“I bought”). If you wanted to stress an ongoing or habitual action, you’d use the imperfective покупал (“I was buying” / “I used to buy”).

Why is новый in that form? Doesn’t its ending change for case?

Adjectives in Russian agree with their nouns in gender, number, and case. Here шампунь is:
• masculine
• singular
• a direct object (accusative case)
Since шампунь is inanimate, its accusative form equals its nominative. Therefore новый stays in the masculine nominative form новый (hard-stem adjective ending -ый).

Why does шампунь end with a soft sign (ь), and how is it declined?