Он всегда дружелюбный, даже когда устал.

In Russian, the verb to be is usually omitted in the present tense.

So:

• Он дружелюбный = He is friendly
• literally, it looks like He friendly

This is completely normal in Russian.
You only use forms of быть more often in the past or future:

• Он был дружелюбный = He was friendly
• Он будет дружелюбный = He will be friendly

So in the present, leaving out is is the standard pattern.

Дружелюбный is an adjective, and it has to agree with the person it describes.

Here the subject is он = he, so the adjective is:

• masculine
• singular
• nominative

That gives дружелюбный.

Compare:

• Он дружелюбный = he is friendly
• Она дружелюбная = she is friendly
• Оно дружелюбное = it is friendly
• Они дружелюбные = they are friendly

So the ending -ый here matches он.

Yes, you can.

Russian often has two possibilities here:

• дружелюбный — long form adjective
• дружелюбен — short form adjective

Both can mean friendly in this sentence.

The difference is mostly stylistic:

• Он всегда дружелюбный sounds natural and conversational.
• Он всегда дружелюбен sounds a bit more formal, literary, or concise.

For a learner, дружелюбный is usually easier and more common to start with.

Устал means got tired / is tired, and in this sentence it works naturally as is tired in English.

It is the past tense masculine singular form of the verb устать.

So:

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

Russian often uses this past-tense form where English uses is tired.

By contrast, уставший is more like tired as a descriptive adjective or participle, as in:

• уставший человек = a tired person

In this sentence, когда устал is the normal way to say when he is tired / when he’s tired.

Russian often omits the subject in the second clause when it is obvious from context.

So:

• Он всегда дружелюбный, даже когда устал.

is understood as:

• Он всегда дружелюбный, даже когда он устал.

The second он is unnecessary because the sentence is clearly still talking about the same person.

Russian does this very often when the subject is easy to understand.

Because когда устал is a subordinate clause: when he is tired.

Russian normally separates subordinate clauses with a comma.

So the structure is:

• Он всегда дружелюбный = main clause
• даже когда устал = subordinate clause

That is why you write:

• Он всегда дружелюбный, даже когда устал.

The comma is required in standard Russian spelling.

Даже means even.

It adds emphasis: not only is he friendly in normal situations, but even in a difficult situation — when he is tired — he is still friendly.

So:

• когда устал = when he is tired
• даже когда устал = even when he is tired

It makes the statement stronger.

Всегда means always, and in this sentence it modifies the whole statement: He is always friendly.

The word order here is very natural:

• Он всегда дружелюбный

Russian word order is more flexible than English, but different orders can change emphasis slightly.

For example:

• Он всегда дружелюбный — neutral, natural
• Он дружелюбный всегда — puts a little more emphasis on always
• Всегда он дружелюбный — possible, but marked and less neutral

So the original order is the most standard one.

It usually suggests a general characteristic: he is a friendly person, and that remains true even when he is tired.

Russian adjectives like дружелюбный often describe a trait or usual quality.

Because of всегда = always, the sentence strongly suggests a habitual or consistent quality, not just a one-time situation.

So it means something like:

• friendliness is part of his normal character
• and tiredness does not change that much

Yes, literally устал is a past-tense form and can mean got tired. But in sentences like this, English often translates it more naturally as when he is tired.

Russian commonly uses forms like устал to describe a resulting state:

• Я устал = I am tired
• literally, something like I became tired

So in this sentence, the most natural English meaning is:

• even when he is tired

not necessarily a dramatic one-time event of becoming tired.

A very literal breakdown would be:

• Он = he
• всегда = always
• дружелюбный = friendly
• даже = even
• когда = when
• устал = got tired / is tired

So a very literal version might be:

• He always friendly, even when tired / even when he got tired

But natural English needs is, so the normal translation becomes:

• He is always friendly, even when he is tired.

This is a good example of how Russian and English structure simple descriptions differently.