Když jsem po běhání hladový, dám si ještě jednu sušenku.

Here když means when.

It introduces a clause that gives the situation or condition:

• Když jsem po běhání hladový = When I’m hungry after running

In many sentences, když can mean either:

• when in a time sense
• if/whenever in a repeated situation

So this whole sentence can feel like:

• When/Whenever I’m hungry after running, I have one more cookie.

Yes. Jsem is the 1st person singular form of být = to be.

So:

• jsem hladový = I am hungry

In Czech, you usually need this verb in normal present-tense statements of this type, unlike in some languages where it might be omitted.

Because hladový is an adjective meaning hungry.

So:

• jsem hladový = I am hungry

Compare:

• mám hlad = I am hungry literally I have hunger
• jsem hladový = I am hungry literally I am hungry

Both are possible in Czech, but they are built differently:

• mám hlad uses the noun hlad
• jsem hladový uses the adjective hladový

A learner should also know that mám hlad is often the more common everyday way to say I’m hungry, but jsem hladový is completely understandable and natural.

Because it agrees with the speaker in gender and number.

Here, hladový is:

• masculine singular

So this version is what a male speaker would normally say.

Other possibilities would be:

• hladová if the speaker is female
• hladové for neuter
• plural forms if talking about more than one person

So a woman would say:

• Když jsem po běhání hladová, dám si ještě jednu sušenku.

Po běhání means after running.

It is made of:

• po = after
• běhání = running

Here běhání is a verbal noun, something like the activity of running.

So:

• po běhání = after running / after a run

This is a very natural Czech way to talk about an activity in general.

Because běhání names the activity itself: running.

A few related forms:

• běhat = to run (imperfective verb)
• běhání = running as an activity
• běh = a run, running, depending on context

So:

• po běhání = after running, after the activity of running
• po běhu = after the run

Both can work, but the nuance is a little different:

• po běhání sounds like after doing some running
• po běhu sounds more like after the run as a specific event

Because po here requires the locative case.

The base noun is:

• běhání

And in this case, the locative form is also:

• běhání

So even though the word looks unchanged, it is still in the correct case after po.

This is something Czech learners meet often: sometimes the case ending is visible, and sometimes the form happens to look the same.

Dám si literally means something like I’ll give myself or I’ll have.

It comes from:

• dám = I give / I will give from dát
• si = a short reflexive pronoun meaning to myself / for myself

In natural English, dám si is often best translated as:

• I’ll have
• I’ll take
• I’ll eat/drink depending on context

So here:

• dám si ještě jednu sušenku = I’ll have one more cookie

This is a very common Czech pattern for food and drink:

• Dám si kávu. = I’ll have a coffee.
• Dám si pivo. = I’ll have a beer.

Because it adds the idea that the action is done for oneself.

Without going too literally, dát si is a standard expression meaning:

• to have
• to take
• to eat/drink

especially when talking about food, drink, or something you choose for yourself.

So:

• dám sušenku would mean I give a cookie
• dám si sušenku means I’ll have a cookie

That is a very important difference.

This is about aspect, which is very important in Czech.

• dát is perfective
• dávat is imperfective

Here dám comes from perfective dát, and it presents the action as a single complete act: having a cookie.

In sentences like this, Czech often uses the perfective present to describe what happens on each occasion:

• Když..., dám si... = When/Whenever..., I have/I’ll have...

It can sound natural even though in English we often use a simple present for habits.

If you used dávám si, it would focus more on the habitual or repeated nature itself, while dám si sounds like the typical complete action that follows in that situation.

Here ještě means still, yet, another, one more, depending on context.

In this sentence, the best meaning is:

• one more
• another

So:

• ještě jednu sušenku = one more cookie / another cookie

This is a very common use of ještě with numbers:

• ještě jeden = one more
• ještě dvě = two more
• ještě trochu = a little more

Because sušenka is a feminine noun, and jednu is the correct form of one in the accusative feminine singular.

Here is the logic:

• sušenka = feminine
• it is the direct object of dám si
• direct objects are often in the accusative
• so jedna changes to jednu

Compare:

• jedna sušenka = one cookie
• mám jednu sušenku = I have one cookie
• dám si jednu sušenku = I’ll have one cookie

Because sušenku is the accusative singular form of sušenka.

The noun is feminine, and it is the direct object of the verb:

• sušenka = nominative
• sušenku = accusative

So:

• To je sušenka. = That is a cookie.
• Dám si sušenku. = I’ll have a cookie.

This is one of the most common feminine noun patterns in Czech:

• nominative -a
• accusative -u

By itself, jednu sušenku means one cookie.

But together with ještě, it usually means:

• one more cookie
• another cookie

So the phrase:

• ještě jednu sušenku

is very naturally understood as:

• another cookie
• one more cookie

Because the sentence has two clauses, and the first one starts with když.

The structure is:

• Když jsem po běhání hladový, = subordinate clause
• dám si ještě jednu sušenku. = main clause

In Czech, subordinate clauses are normally separated by a comma. This is standard punctuation.

Yes, Czech word order is flexible, though some versions sound more natural than others.

The given sentence is very natural:

• Když jsem po běhání hladový, dám si ještě jednu sušenku.

You could also say:

• Ještě jednu sušenku si dám, když jsem po běhání hladový.

But that changes the emphasis. It sounds more marked, as if you are stressing one more cookie.

So the original word order is a good neutral model for learners.

Most naturally, it expresses a habitual repeated situation:

• Whenever I’m hungry after running, I have one more cookie.

Because dám is perfective, it can also feel a bit like I’ll have in English, but in this kind of sentence the overall meaning is usually general and repeated.

So the best way to understand it is:

• When/Whenever this situation happens, this is what I do.

Almost, but she would normally change hladový to hladová.

So a female speaker would usually say:

• Když jsem po běhání hladová, dám si ještě jednu sušenku.

The rest of the sentence stays the same.

Usually yes, but the exact English word can vary a bit by context.

Sušenka can mean:

• cookie
• sometimes biscuit

depending on the kind of snack and the variety of English being used.

For an American English learner, cookie is usually the best default. For a British English learner, biscuit may sometimes fit better.