Я сохранил счёт из ресторана на всякий случай.

Сохранил is the masculine past tense singular of the verb сохранить (to keep / to preserve / to save).

• сохранить = perfective aspect (a completed, one-time action)
• Past tense endings: сохранил (m), сохранила (f), сохранило (n), сохранили (pl)

Yes. In Russian, past tense verbs agree in gender/number with the subject. With я, the gender is the speaker’s gender:

• male speaker: я сохранил
• female speaker: я сохранила
• plural we: мы сохранили

It’s mainly aspect:

• сохранить (perfective) = kept/saved (successfully, as a completed action) → fits I kept it (once)
• сохранять (imperfective) = to keep/save (as a process/habit/repeatedly)
  Examples:
• Я сохранил счёт. = I saved the bill (one completed action).
• Я всегда сохраняю счета. = I always keep bills (habit).

Счёт can mean several things (account, score, count), but in a restaurant context it commonly means the bill (the amount to pay).
So счёт из ресторана is understood as the restaurant bill.

Common distinction:

• счёт = the bill presented by the restaurant (often a printed item listing what you owe)
• чек = the receipt proving payment (cash register receipt / fiscal receipt)

In real life, people more often keep a чек as proof they paid. But they might also keep счёт (especially if it functions like an itemized bill or for expenses). Depending on the situation, either could make sense.

Because сохранить takes a direct object in the accusative case: to keep/save what? → счёт.
For masculine inanimate nouns like счёт, the accusative form equals the nominative: счёт.

Both are possible but with different nuance:

• из ресторана = from the restaurant (origin/source: the bill that came from that place)
• в ресторане = in the restaurant (location where the bill is/was, or where the action happened)

In this sentence, счёт из ресторана sounds like the bill from the restaurant (the restaurant-issued bill).

ресторана is genitive singular, triggered by the preposition из (meaning from/out of), which requires the genitive:

• из
  • Genitive → из ресторана

Literally it’s like for any case/occasion, but idiomatically it means just in case / to be on the safe side.
It’s a fixed phrase and extremely common in everyday Russian.

It’s accusative: на + accusative is often used to express purpose/for-ness here (for what?).

• на
  • Acc → на случай
    всякий agrees with случай: masculine, singular, accusative (inanimate → same as nominative).

Yes, Russian word order is flexible and changes emphasis:

• Я сохранил счёт из ресторана на всякий случай. = neutral, “I kept the restaurant bill just in case.”
• На всякий случай я сохранил счёт из ресторана. = highlights the motivation first (“Just in case, I kept…”).
• Счёт из ресторана я сохранил на всякий случай. = emphasizes the object (“The bill is what I kept…”).

Typical stress:

• Я (ya)
• сохрани́л (sakhra-NEEL) — stress on -нил
• счёт (shchyot) — one syllable
• рестора́на (resta-RA-na) — stress on -ра-
• вся́кий (VSYA-kiy) — stress on вся́
• слу́чай (SLOO-chay) — stress on слу́-