Он явно устал.

In Russian, the verb to be is usually not expressed in the present tense.

So where English says:

• He is tired

Russian simply says:

• Он устал

The idea of is is understood automatically.

You only normally see forms of быть in the past or future, or in certain special constructions.

For example:

• Он был усталым = He was tired
• Он будет усталым = He will be tired

But in the present:

• Он устал = He is tired / He has gotten tired

Явно is an adverb. In this sentence it means something like:

• clearly
• obviously
• evidently
• apparently (depending on context)

So Он явно устал means that the speaker can tell from some evidence — maybe his face, voice, or behavior — that he is tired.

A useful nuance:

• явно often suggests it is easy to notice
• it can sound a little more observational than purely logical

Here, устал is a verb form, not an adjective.

It is the past tense masculine singular form of the verb устать, which means to become tired.

So literally, Он устал is closer to:

• He became tired
• He got tired

But in normal English, this often corresponds to:

• He is tired

That happens because Russian often uses a past perfective verb to describe a resulting present state.

Compare:

• Он устал = He got tired / He is tired now
• Он уставший = He is a tired person / he looks tired as a descriptive quality

So in this sentence, Russian prefers the verb form устал.

The infinitive is устать.

It is a perfective verb.

That matters because Russian aspect shows how the action is viewed:

• устать = perfective, to become tired, reach the state of tiredness
• уставать = imperfective, to get tired, to be getting tired, or to get tired regularly

Examples:

• Он устал = He got tired / He is tired now
• Он уставал на работе = He used to get tired at work / He would get tired at work
• Он уставал весь день = He was getting tired all day

So in Он явно устал, the perfective verb shows a completed change into the state of being tired.

In the Russian past tense, verbs usually agree with the subject in gender and number.

So from устать, you get:

• он устал = he got tired / he is tired
• она устала = she got tired / she is tired
• оно устало = it got tired
• они устали = they got tired / they are tired

So the -л part marks past tense, and the ending changes depending on who or what the subject is.

Yes.

Он устал is a complete sentence by itself.

Adding явно changes the meaning slightly:

• Он устал = He is tired.
• Он явно устал = He is clearly / obviously tired.

So явно is not required grammatically; it just adds the speaker’s judgment that the tiredness is noticeable.

Sometimes yes.

Russian often drops subject pronouns when the subject is clear from context.

So in the right situation, you could simply say:

• Явно устал.

This might mean:

• He’s clearly tired.
• You’re clearly tired.
• I’m clearly tired.

The exact subject would depend on the conversation.

However, if you want to be clear and neutral, especially for a learner, Он явно устал is the safest full form.

Yes, Russian word order is flexible, but different orders sound different in emphasis.

The most neutral version here is:

• Он явно устал.

This presents he as the topic and says that he is clearly tired.

You could also hear:

• Явно, он устал.
  This is more like Clearly, he’s tired or Apparently, he’s tired.

Russian word order often changes to highlight different parts of the sentence, but not every permutation sounds equally natural in every context. For a learner, Он явно устал is the best default choice.

The stress is:

• Он я́вно уста́л.

A rough pronunciation guide:

• Он ≈ on
• я́вно ≈ YAV-na
• уста́л ≈ oo-STAL

Notes:

• я in я́вно sounds like ya
• the final л in устал is a normal Russian l sound
• Russian stress is important, because it is not always predictable

So the full sentence is pronounced approximately:

• on YAV-na oo-STAL