reizouko de otya wo hiyasite kara, suitou ni iremasu.

This is a very common question.

Here, 冷蔵庫で means in/using the refrigerator as the place where the action happens. The particle で marks the location of an action.

• 冷蔵庫で冷やす = to chill something in the refrigerator
• The action is 冷やす.

By contrast, に often marks:

• a destination
• a point in time
• the location where something exists, rather than where an action happens

So:

• 冷蔵庫にある = it is in the refrigerator
• 冷蔵庫で冷やす = chill it in the refrigerator

That is why で is correct here.

Because お茶 is the direct object of the verb 冷やす.

• 冷やす is a transitive verb: it means to chill/cool something
• The thing being chilled is お茶
• So it takes を

Structure:

• お茶を冷やす = chill the tea

Later in the sentence, that same tea is what gets put into the bottle.

The dictionary form is 冷やす.

冷やして is the て-form of 冷やす.

Conjugation:

• 冷やす → 冷やして

This is a regular -す verb pattern:

• 話す → 話して
• 出す → 出して
• 冷やす → 冷やして

In this sentence, the て-form is used as part of ～てから.

～てから means after doing X, then do Y.

So the structure is:

• 冷やしてから、入れます
• After chilling it, I put it in

This pattern shows a clear sequence:

1. First chill the tea
2. Then put it into the bottle

It often implies that the first action is completed before the second one happens.

Examples:

• 手を洗ってから、食べます。
  After washing my hands, I eat.
• 宿題をしてから、寝ます。
  After doing homework, I go to bed.

Good question. Both can connect actions, but ～てから is more explicit.

• 冷やして、入れます = chill it and put it in
• 冷やしてから、入れます = after chilling it, put it in

With ～てから, the order is emphasized more clearly. It often suggests:

• the first action must happen before the second
• the second action follows after the first is completed

So ～てから is a little more precise than plain ～て.

Because に marks the destination or target location of 入れる.

• 入れる = to put something into something
• The thing being put somewhere is omitted here, but it is understood to be the tea
• The destination is 水筒

So:

• 水筒に入れます = put it into the bottle

This is the same pattern as:

• 箱に入れる = put it in a box
• かばんに入れる = put it in a bag

Because this sentence means to put something into the bottle, not to go into the bottle by itself.

There is an important transitive/intransitive pair here:

• 入れる = to put something in
• 入る = to enter / to go in

So:

• 水筒にお茶を入れます = I put tea into the bottle
• お茶が水筒に入ります = The tea goes into the bottle / fits into the bottle

In your sentence, the speaker is performing the action, so 入れます is the correct verb.

The subject is omitted, which is very normal in Japanese.

Japanese often leaves out information that is obvious from context. So this sentence could mean:

• I chill the tea in the refrigerator, then put it into a bottle
• We chill the tea...
• You chill the tea...

depending on the situation.

In many learning materials, it is often understood as I unless context says otherwise.

Because Japanese often omits repeated information when it is already clear.

A fuller version would be:

• 冷蔵庫でお茶を冷やしてから、水筒にお茶を入れます。

But repeating お茶 sounds unnecessary here, because everyone already knows what is being put into the bottle.

So the shorter sentence is more natural:

• 冷蔵庫でお茶を冷やしてから、水筒に入れます。

The omitted object is understood from the earlier clause.

Yes, the お in お茶 is an honorific or polite prefix, but in some words it is so common that the prefixed form feels like the normal everyday word.

• お茶 is the standard everyday way to say tea
• 茶 by itself does exist, but it sounds more technical, compound-like, or less natural in many everyday contexts

For a learner, it is best to think of お茶 as the normal word to use in conversation.

Other common words like this include:

• お水
• お酒
• お金

Not every お- word is super formal; sometimes it is just the usual form.

Japanese -ます forms do not distinguish present and future the same way English does.

So 入れます can mean:

• I put it in
• I will put it in

In this sentence, because it describes a sequence of actions, it is usually understood as a future or habitual action, depending on context:

• as instructions
• as a routine
• as a planned action

Japanese relies heavily on context for time reference.

Yes. 冷やす broadly means to make something cold/cooler.

Depending on context, it can be translated as:

• cool
• chill
• refrigerate

In this sentence, because the place is 冷蔵庫, chill is the most natural translation.

A related word is 冷ます, which means to let something cool down or to cool something from hot to less hot.

Very roughly:

• 冷やす often focuses on making something cold
• 冷ます often focuses on reducing heat

But there is some overlap, and context matters.

The comma in:

• 冷やしてから、水筒に入れます。

is mainly a writing aid. It shows a pause and makes the sentence easier to read.

It is not required every time. You may also see:

• 冷蔵庫でお茶を冷やしてから水筒に入れます。

Both are fine. Japanese punctuation is often more flexible than English punctuation.

Yes. A more explicit version would be:

• 冷蔵庫でお茶を冷やしてから、水筒にお茶を入れます。

Or even, if the subject were added:

• 私は冷蔵庫でお茶を冷やしてから、水筒にお茶を入れます。

But Japanese usually prefers the shorter version when the omitted information is obvious from context. That is why the original sentence sounds natural.