kare ha hurui syasin wo sakuzyosite kara, atarasii pasuwaado wo kimemasita.

は marks 彼 as the topic of the sentence.

So 彼は means something like as for him or more naturally just he in English. Japanese often separates the topic of the sentence from the rest of the information. Here, the sentence is about what he did.

In Japanese, adjectives normally come before the noun they describe.

• 古い写真 = old photos / an old photo
• 新しいパスワード = new password

This is similar to English word order in this case.
Also, 古い and 新しい are い-adjectives, so they can directly modify a noun without any extra word.

を marks the direct object of a verb, meaning the thing directly affected by the action.

• 写真を削除して = delete the photos
• パスワードを決めました = decided on / set the password

So in this sentence, the things being acted on are:

• 写真 for 削除する
• パスワード for 決める

削除して is the て-form of 削除する.

Breakdown:

• 削除する = to delete
• 削除して = deleting / delete and ... / after deleting ...

Because 削除する is a する-verb, its て-form is made by changing する to して:

• する → して
• 削除する → 削除して

In this sentence, it is followed by から, so 削除してから means after deleting.

てから means after doing X, then do Y.

So:

• 削除してから、決めました = after deleting, he decided

This pattern emphasizes the order:

1. delete the old photos
2. then decide on the new password

It is a very common way to show that one action happens first, and the next happens afterward.

The plain て-form can connect actions, but it does not always emphasize strict sequence as strongly as てから does.

Compare:

• 写真を削除して、パスワードを決めました = deleted the photos and decided on the password
• 写真を削除してから、パスワードを決めました = after deleting the photos, decided on the password

With てから, the speaker more clearly shows that the second action happened only after the first one.

All three can fit depending on context.

決める basically means to decide or to determine. With パスワード, it often means:

• decided on a new password
• chose a new password
• set a new password

So the core Japanese idea is made a decision about the password.
English translation may vary depending on what sounds most natural in context.

Because the sentence describes completed actions.

• 削除してから = after deleting
• 決めました = decided

Japanese often puts the tense marking on the main final verb of the sentence. Here, 決めました shows that the overall event is in the past and is stated politely.

Also, ました is the polite past ending of the verb:

• 決める → plain dictionary form
• 決めました → polite past

Japanese often leaves out information that is clear from context.

In English, we often need words like his, her, the, or a. Japanese does not always require them. If the context already makes it obvious that these are his old photos and his new password, Japanese can simply say:

• 古い写真
• 新しいパスワード

This is very natural in Japanese.

It can be either photo or photos. Japanese nouns usually do not change form for singular vs. plural.

So 古い写真 could mean:

• an old photo
• old photos

You figure it out from context or from the translation already given. Japanese often leaves number unspecified unless it matters.

The comma is mainly for readability.

Japanese punctuation is often more flexible than English punctuation. After a longer introductory part like:

• 古い写真を削除してから、

a comma helps separate that part from the main action:

• 新しいパスワードを決めました。

It is not a special grammar marker by itself here; it just makes the sentence easier to read.

They are almost certainly added for learners.

Normal Japanese writing usually does not put spaces between words:

彼は古い写真を削除してから、新しいパスワードを決めました。

Teaching materials sometimes add spaces to help beginners see the parts of the sentence more clearly.