Learn Hardcore Ukrainian: Заспокойся, будь ласка, ми вже знайшли ліки. - Calm down, please; we have already found the medicine.

The standard form is заспокойся (imperative of заспокоїтися “to calm down”). In the imperative, the -ї- typically becomes -й-: compare надіятися → надійся. The form заспокійся is a common mistake and is considered non‑standard. You may also see the contracted reflexive variant заспокойсь; it’s acceptable but more colloquial, while заспокойся is the safest choice.

Why is будь ласка surrounded by commas here, and where else can it go?

Будь ласка is a parenthetical politeness marker and is set off by commas when it appears inside a sentence: Заспокойся, будь ласка, ми вже знайшли ліки. You can place it:

At the beginning: Будь ласка, заспокойся, ми вже знайшли ліки.
In the middle (as in the example), with commas on both sides.
At the end: Заспокойся, будь ласка. (Only the comma before it, since the sentence ends there.)

Why is the past tense знайшли used to mean “have already found”?

Ukrainian doesn’t have a separate present perfect tense. Instead, it uses the past tense of a perfective verb plus вже/уже to express English “have + past participle.” So ми вже знайшли literally “we already found” corresponds to “we have already found.”

What aspect is знайшли, and what’s the imperfective partner?

Знайшли is past plural, perfective, from знайти “to find (once/completely).” Its imperfective partner is знаходити “to find (be finding, find habitually).” Use perfective for a completed result: ми вже знайшли; use imperfective for ongoing/habitual: ми часто знаходимо “we often find.”

Does ліки have a singular? What case is it in here?

Ліки is a plural‑only noun (pluralia tantum); there is no singular form. In this sentence it’s the direct object in the accusative plural, which looks the same as the nominative plural: ліки. With quantities you’ll see the genitive plural: багато ліків “a lot of medicine/medications.”

Can I use лікарство or медикаменти instead of ліки?

Yes, with nuance:

Ліки = “medicine/medications” (general, plural‑only).
Лікарство = “a medicine/a remedy” (singular, one item/type), e.g., ми вже знайшли лікарство “we’ve already found the medicine (a specific one).”
Медикаменти/препарати = “medications/drugs” (more formal/clinical).

Can I drop the subject pronoun ми?

You can say вже знайшли ліки, but it’s ambiguous between “we (have) found” and “they (have) found,” because past plural (-ли) doesn’t mark person. Keeping ми avoids that ambiguity. In contexts where it’s clear who “found,” dropping ми is fine.

How do I make it polite/formal or address more than one person?

Use the plural/polite imperative of the reflexive verb:

Заспокойтеся, будь ласка, ми вже знайшли ліки. You’ll also hear заспокойтесь (contracted reflexive), which is widespread in speech, but заспокойтеся is the fully standard form.

Is уже acceptable instead of вже?

Yes. Вже and уже are synonyms; both are correct. Вже is more common in contemporary usage, but there’s no difference in meaning: ми вже/уже знайшли ліки.

Could I use a dash instead of a comma before ми вже знайшли ліки?

Yes, to signal an explanatory or assuring tone: Заспокойся, будь ласка — ми вже знайшли ліки. The plain comma is also correct; the dash just adds a pause/emphasis.

Where does the stress fall, and how do I pronounce this?

заспоко́йся: stress on -ко́й-; roughly “zah-spo-KOY-sya.”
бу́дь ла́ска: both words stressed; “bood’ LA-ska.”
знайшли́: stress on -ли́; “znai-shLY.”
лі́ки: stress on лі; “LEE-ky.”

What does the -ся in заспокойся do? What happens if I remove it?

The postfix -ся marks the verb as reflexive: заспокоїтися “to calm oneself down.” Without it, заспокоїти means “to calm (someone/something).” Compare:

Заспокойся, будь ласка. “Calm down (yourself), please.”
Заспокой його, будь ласка. “Calm him down, please.”

Is будь-ласка with a hyphen correct?

No. The correct spelling is two separate words: будь ласка. No hyphen.

Could I say Вже ми знайшли ліки instead of Ми вже знайшли ліки?

It’s possible but marked. Ми вже знайшли ліки is the neutral word order. Вже ми знайшли… sounds emphatic/poetic or rhetorical, not the default in everyday speech.