watasi ha douryou wo sinraisite imasu.

は marks 私 as the topic of the sentence. It sets up what the sentence is about: as for me...

So 私は does not simply mean I in a neutral grammatical sense; it gives a topic-comment structure:

• 私は = As for me
• 同僚を信頼しています = trust my coworker / trust my coworkers

In many beginner sentences, は is translated as part of the subject, but its actual job is to mark the topic.

Yes. Very often, Japanese leaves out subjects and topics when they are clear from context.

So in a normal conversation, people might simply say:

• 同僚を信頼しています。

That can still mean I trust my coworker / coworkers, depending on the situation.

Including 私 can make the sentence clearer, more contrastive, or slightly more explicit than Japanese usually needs.

Because 信頼する normally takes a direct object marked by を.

So:

• 同僚を信頼する = to trust a coworker / coworkers

This is different from some English patterns where learners may expect something like to or another particle. In Japanese, 信頼する is commonly used with を.

Examples:

• 友達を信頼しています。 = I trust my friend.
• 部下を信頼しています。 = I trust my subordinates.

The dictionary form is 信頼する.

This is a する-verb:

• 信頼 = trust, reliance
• する = to do

Together:

• 信頼する = to trust

Then:

• 信頼している = plain progressive/resultative form
• 信頼しています = polite form

This is a very common question.

With many verbs, 〜ている can mean an ongoing action, but with some verbs it describes a continuing state or condition. 信頼する often works that way.

So:

• 信頼します can sound like a more general statement, a future decision, or a formal declaration depending on context.
• 信頼しています usually sounds more natural for describing your current state of trust: I trust ...

In other words, 〜ている here is not just I am trusting in the English progressive sense. It often means I am in a state of trusting.

Not exactly.

Both can be translated as trust or believe, but the nuance is different:

• 信じる / 信じています often means to believe
• 信頼する / 信頼しています means to trust, often with a stronger sense of confidence in someone's character, ability, or reliability

So:

• 彼の話を信じています。 = I believe what he says.
• 彼を信頼しています。 = I trust him.

In your sentence, 信頼しています suggests confidence in the coworker as a person, not just belief in one statement.

It can mean either, depending on context.

Japanese nouns usually do not show singular vs. plural the way English does. So:

• 同僚を信頼しています。

could mean:

• I trust my coworker
• I trust my coworkers
• I trust a coworker
• I trust coworkers

The surrounding context tells you which is intended.

Japanese often leaves that kind of information unstated when it is obvious from context.

English usually requires something like:

• my coworker
• the coworker
• a coworker

Japanese does not require articles like a or the, and possessives like my are often omitted if the relationship is clear.

So 同僚 by itself can cover several English possibilities.

If needed, Japanese can be more explicit:

• 私の同僚 = my coworker

But in many cases, just 同僚 is perfectly natural.

Yes. 信頼しています is polite because it uses います.

Compare:

• 私は同僚を信頼しています。 = polite
• 私は同僚を信頼している。 = plain

The polite version is suitable in normal conversation, workplace speech, and many formal situations.

Also, the word 信頼 itself sounds somewhat formal or serious, so the whole sentence has a fairly mature, professional tone.

Yes, to some extent.

Japanese word order is more flexible than English as long as the particles stay attached to the correct words.

For example:

• 私は同僚を信頼しています。
• 同僚を私は信頼しています。

Both are possible, but they have slightly different emphasis.

The most neutral order is usually:

• 私は同僚を信頼しています。

Or, if the topic is already understood:

• 同僚を信頼しています。

So the particles are what matter most for understanding the roles of the words.

It is read:

• 私 → わたし
• は → は but pronounced わ
• 同僚 → どうりょう
• を → を often pronounced お
• 信頼して → しんらいして
• います → います

So the full reading is:

わたし は どうりょう を しんらいして います。

In natural speech, it sounds like:

わたしは どうりょうを しんらいしています。

Yes, but it sounds a bit formal and deliberate.

Because 信頼する is a somewhat serious word, the sentence can feel stronger and more formal than a casual English I trust my coworker.

In everyday casual speech, people might still say it, especially in a workplace or serious discussion. But depending on context, other expressions could also appear.

So this sentence is natural, especially when talking seriously about professional relationships, reliability, or confidence in someone.