Češu kočku, když si olizuje srst.

Češu is the 1st person singular present tense form of česat, meaning to comb or to brush.

So češu = I comb / I am combing / I brush / I am brushing.

A learner may also notice that the form does not look exactly like the infinitive:

• infinitive: česat
• present stem: češ-
• 1st singular: češu

That stem change is normal for this verb.

Because kočku is in the accusative singular, which is the case used for the direct object.

In this sentence, the cat is the thing being brushed, so Czech uses the accusative:

• kočka = nominative singular, the dictionary form, usually used for the subject
• kočku = accusative singular, used here because the cat is the object of češu

So:

• Kočka... = The cat...
• Češu kočku. = I brush the cat.

Czech often leaves out subject pronouns when they are already clear from the verb form.

Here, češu already tells you the subject is I, so já is unnecessary.

• Češu kočku. = normal, natural
• Já češu kočku. = possible, but more emphatic, like I am the one brushing the cat

This is very common in Czech.

For the same reason: Czech often omits subject pronouns when the meaning is clear from context and verb ending.

In olizuje, the verb is 3rd person singular: he/she/it licks / is licking.
From the context, we understand that the subject is the cat.

So Czech does not need to say ona here.

• když si olizuje srst = when/while it is licking its fur

If you added ona, it would usually sound more emphatic than necessary.

Here když can be understood as when or while, depending on how you interpret the situation.

In many sentences, když introduces a time clause and can cover both ideas:

• when something happens
• while something is happening

So this sentence can suggest either:

• a general situation: I brush the cat when it licks its fur
• an overlapping action: I brush the cat while it is licking its fur

The exact nuance often comes from context rather than from když alone.

Because když si olizuje srst is a subordinate clause, and Czech normally separates subordinate clauses with a comma.

So the structure is:

• main clause: Češu kočku
• subordinate clause: když si olizuje srst

That is why the comma is required:

Češu kočku, když si olizuje srst.

If the order were reversed, there would still be a comma:

Když si olizuje srst, češu kočku.

Si is the reflexive dative pronoun. In this sentence, it shows that the cat is doing something to its own fur.

So:

• olizuje si srst = it licks its fur / its own fur

This is a very common Czech pattern with body parts, clothing, and things closely connected to the subject.

Literally, it is something like:

• it licks fur to itself

That literal wording is not natural English, but it helps explain the grammar.

Without si, the sentence would be less clearly about the cat’s own fur.

Here srst is in the accusative singular, because it is the direct object of olizuje si.

The reason it looks unchanged is that for this type of noun, the nominative singular and accusative singular are the same.

So:

• nominative: srst
• accusative: srst

This is normal for feminine nouns of this pattern.

Yes. Both verbs here are imperfective:

• česat → češu
• olizovat → olizuje

That matters because the imperfective aspect is the normal choice for:

• ongoing actions
• repeated or habitual actions
• background actions

That fits this sentence well. The cat’s licking and the brushing are presented as actions in progress or as a general repeated situation.

If you used a perfective verb instead, the meaning would shift toward a single completed action, and the sentence would sound different.

Yes. Czech word order is fairly flexible, and you can move the clauses around.

For example:

• Češu kočku, když si olizuje srst.
• Když si olizuje srst, češu kočku.

Both are grammatical.

The difference is mostly about emphasis and information flow:

• starting with Češu kočku puts the brushing first
• starting with Když si olizuje srst puts the time/background first

Inside each clause, word order can sometimes also shift, but the most neutral version is the one you were given.

Strictly speaking, kočka is the ordinary word for a female cat, while kocour is a male cat.

However, in many learning examples and in some everyday contexts, kočka can function as a general word for cat, especially when the sex is not important.

So a learner should know both facts:

• exact lexical meaning: kočka = female cat
• practical classroom meaning: often just cat

In this sentence, the important grammar point is that kočka is a feminine noun, which affects its case forms such as kočku.