Někteří psi štěkají v noci.

Because psi is a masculine animate plural noun, and některý has to agree with it.

In the nominative plural:

• masculine animate: někteří
• masculine inanimate: některé
• feminine: některé
• neuter: některá

So:

• někteří psi = some dogs
• někteří muži = some men

In Czech, animals like dogs are treated as animate nouns.

Yes, it is irregular. The noun pes means dog, and its nominative plural is psi.

This is just a pattern you need to learn:

• pes = dog
• psi = dogs

A few other forms:

• bez psa = without a dog
• bez psů = without dogs
• vidím psa = I see a dog
• vidím psy = I see dogs

You may also see psové, but psi is the normal everyday form.

Because štěkají is the 3rd person plural present tense form of štěkat, meaning to bark.

Here is the basic pattern:

• já štěkám = I bark
• ty štěkáš = you bark
• on/ona štěká = he/she barks
• oni/ony štěkají = they bark

Since the subject is někteří psi = some dogs, the verb has to be plural: štěkají.

Because the preposition v here takes the locative case, and noc changes to noci in the singular locative.

So:

• dictionary form: noc = night
• after v: v noci = at night / in the night

This is a very common time expression. It does not mean motion into something; it means the time when something happens.

Usually it means at night, in a general time sense.

So Někteří psi štěkají v noci is most naturally understood as a general statement like Some dogs bark at night.

Depending on context, it can also feel like during the night, but in everyday English at night is usually the best match.

Because Czech does not have articles like English a/an and the.

Czech usually shows definiteness through:

• context
• word order
• demonstratives such as ten, if needed
• words like někteří, which already give information such as some

So Czech can simply say:

• psi = dogs / the dogs
• někteří psi = some dogs

Yes. Czech word order is quite flexible.

The neutral order here is:

• Někteří psi štěkají v noci.

But other orders are possible:

• V noci někteří psi štěkají. = emphasizes at night
• Štěkají v noci někteří psi. = more marked, less neutral

The basic meaning stays similar because the endings show the grammar, but the word order changes what is emphasized.

A rough guide:

• někteří ≈ NYEK-te-rzhee
• štěkají ≈ SHTYE-ka-yee

A few useful points:

• ně sounds roughly like nye
• š sounds like English sh
• ř is a special Czech sound; English does not really have it
• á and í are long vowels

You do not need a perfect ř immediately; learners usually work on that gradually.

No, there is a difference.

• psi štěkají v noci = dogs bark at night / dogs are barking at night
• někteří psi štěkají v noci = some dogs bark at night

So někteří makes it clear that you mean only part of the group, not dogs in general.

Most naturally, it sounds like a general or habitual statement:

• Some dogs bark at night.

Czech present tense can also describe what is happening now, but with v noci and this kind of sentence, the habitual meaning is the most likely one unless the context says otherwise.