Learn Hardcore Russian: Тебе нужно следовать плану.

The word нужно is an impersonal predicate meaning “it is necessary.” In such constructions the person who needs to do something is put in the dative case. So тебе literally means “to you,” i.e. “you need.”

What part of speech is нужно, and how does it work here?

нужно is an impersonal modal word (technically an indeclinable adverb/predicate) conveying necessity. There is no overt subject; the construction tells us “it is necessary” and the dative pronoun indicates who must act.

Why is следовать in the infinitive form?

After modal expressions like нужно, Russian uses the infinitive of the main verb to show what action is required. So нужно следовать means “one needs to follow.”

Why is плану in the dative case rather than accusative?

The verb следовать (“to follow, to obey”) takes a dative object when it means “to adhere to something.” Therefore план becomes плану (dative singular).

Could I say следовать за планом instead? What’s the difference?