Yes, it is irregular. The noun pes means dog, and its nominative plural is psi.
This is just a pattern you need to learn:
A few other forms:
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:
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:
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:
So Czech can simply say:
Yes. Czech word order is quite flexible.
The neutral order here is:
But other orders are possible:
The basic meaning stays similar because the endings show the grammar, but the word order changes what is emphasized.
A rough guide:
A few useful points:
You do not need a perfect ř immediately; learners usually work on that gradually.
Most naturally, it sounds like a general or habitual statement:
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.