Learn Hardcore Russian: Хороший водитель всегда соблюдает правила дорожного движения. - A good driver always follows the traffic rules.

Because it must agree in gender, number, and case with the noun водитель (“driver”), which is masculine singular in the nominative. In Russian, adjectives always match the noun they describe.

What tense and aspect is the verb соблюдает in, and what does it mean here?

Соблюдает is the third-person singular present form of the imperfective verb соблюдать. In this sentence, it means that a good driver habitually "follows" or "observes" the traffic rules.

What is the grammatical structure of правила дорожного движения?

Правила is in the Accusative plural (which, for inanimate nouns, looks like the nominative plural) and serves as the direct object of соблюдает. The phrase дорожного движения is a genitive singular modifier that specifies what kind of rules these are—namely, the rules of road traffic. This is a common way in Russian to form compound noun phrases using the genitive to indicate possession or specification.

Why is дорожного in singular form even though правила is plural?

Because правила дорожного движения is a fixed expression meaning “traffic rules.” The noun движение (“traffic/motion”) is used in the genitive singular after правила to indicate the type of rules. This structure—using a singular genitive to modify a plural noun—is standard in many compound expressions in Russian.

Can всегда be placed in a different position in the sentence, or is its placement fixed?

Russian word order is relatively flexible. In this sentence, всегда (“always”) is placed after the subject for a natural rhythm and to emphasize the habitual nature of the action. However, it could be moved (for example, before the verb) without changing the overall meaning, although slight nuances in emphasis might result.

Does the verb соблюдать require a preposition before its object as seen in English with “follow the rules” versus “comply with the rules”?

No, it does not. In Russian, соблюдать directly takes its object without the need for a preposition. So instead of saying “comply with the traffic rules,” the structure is simply “follow the traffic rules” (i.e., соблюдает правила дорожного движения).