Learn Hardcore Ukrainian: Вам варто перевірити розклад, бо черга велика. - You formal should check the schedule because the queue is long.

Because варто is an impersonal predicative (“it is advisable/it’s worth”), and in Ukrainian such predicates take the experiencer in the dative case.

Patterns: Мені/Тобі/Йому/Нам/Вам/Їм варто + infinitive
So: Вам варто перевірити… = “For you, it’s advisable to check…”

Is Вам formal “you” or plural “you”?

Both. Вам can address one person politely/formally or several people. Informal singular would be Тобі:

Formal/polite or plural: Вам варто…
Informal singular: Тобі варто…

What nuance does варто have compared to треба/потрібно/слід/мусите?

варто: a recommendation; mild and polite (“it would be wise/advisable”).
слід: “should/ought to,” somewhat formal/neutral.
треба/потрібно: “need to/have to,” stronger necessity.
мусите/мусиш: “must,” strong obligation.
Softer variants with варто: Вам варто було б… or Можливо, вам варто…

Why is it перевірити (perfective) and not перевіряти (imperfective)?

Perfective (перевірити) focuses on a single, completed action (check it once and be done). Imperfective (перевіряти) would imply a repeated/habitual action.

One-time advice: Вам варто перевірити розклад.
Habitual advice: Вам варто перевіряти розклад.

What case is розклад in, and why does it look like the dictionary form?

It’s the accusative singular (direct object of перевірити). For masculine inanimate nouns, the accusative = nominative, so розклад doesn’t change form here.

Should I use розклад or графік for “schedule”?

розклад: a timetable, especially for transport or classes (e.g., розклад руху, розклад занять).
графік: a work schedule/roster or planned timetable for tasks; also “graph/chart” in other contexts. In this sentence, розклад is the natural choice.

Why is there a comma before бо? Can I use тому що instead?

Ukrainian puts a comma before бо because it introduces a reason clause: …, бо …
тому що and оскільки also introduce reasons; they’re fine here and still take a comma before them: …, тому що … / …, оскільки …
Nuance: бо is short and conversational; тому що is neutral; оскільки is more formal.

Is there any difference between черга велика and велика черга?

Both are grammatical, but:

черга велика = “the queue is big” (predicate emphasis).
велика черга = “a big queue” (attributive emphasis, “there’s a big queue”). Your sentence states a fact about the queue’s size.

Would довга черга be better than велика черга/черга велика?

Both work, with a slight nuance:

велика черга / черга велика = many people; a “big” queue.
довга черга / черга довга = physically long, typically implying a long wait. Either is idiomatic; choose based on what you want to emphasize.

Does черга mean “queue” or “turn”?

Both, depending on context:

“Queue/line”: стояти в/у черзі (to stand in line), без черги (skip the line).
“Turn”: Твоя черга. (It’s your turn.) Here it clearly means a queue/line.

How do you pronounce and stress the words?

Вам [vam] — stress on the only syllable.
ва́рто [ˈvarto] — stress on ва.
переві́рити [pereˈvirɪtɪ] — stress on ві.
ро́зклад [ˈrosklad] — stress on ро; note devoicing: зк sounds like [ск].
бо [bo].
черга́ [t͡ʃerˈɦa] — stress on га; г is a voiced [ɦ].
вели́ка [weˈlɪka] — stress on ли. (Ukrainian в is often [ʋ]/[w]-like.)

Can I change the word order?

Yes, Ukrainian is flexible with word order for emphasis:

Neutral: Вам варто перевірити розклад, бо черга велика.
Fronting the object: Розклад вам варто перевірити, бо черга велика.
Alternative in the reason clause: …, бо велика черга. Keep the comma before the reason clause introduced by бо/тому що/оскільки.