Paní na recepci mi klidně vysvětlila, kde je náš pokoj a kde je hlavní vchod.

Czech does not have articles. So nouns like paní, pokoj, and vchod can mean a or the depending on context.

In this sentence, the context makes them definite, so in natural English you would usually say the lady at reception, our room, and the main entrance.

Literally, it means the lady at the reception.

In natural English, you might translate it as:

• the woman at the front desk
• the receptionist

Paní is a polite word for an adult woman, similar to lady or madam depending on context.

Czech often uses na with places understood as a service point, workplace, or institution.

So na recepci means at reception / at the front desk.

Compare:

• na recepci = at the reception desk, at the service point
• v recepci = in the reception area/room physically

So na recepci is the normal idiomatic choice here.

It is locative singular.

The noun is recepce. After na when it means location, Czech uses the locative:

• na recepci = at reception

So:

• dictionary form: recepce
• locative singular: recepci

Mi means to me.

It is the short unstressed dative form of já:

• mně = full/stressed form
• mi = short unstressed form

So Paní na recepci mi vysvětlila... means The lady at reception explained to me...

Because mi is a clitic. In Czech, short unstressed words like mi, ti, mu, se, si usually go in the second position of the clause.

Here the first unit is Paní na recepci, and then the clitic comes right after it:

• Paní na recepci mi klidně vysvětlila...

This word order is very typical in Czech.

Here klidně means calmly, in a relaxed way, or patiently.

It comes from klidný, meaning calm.

So the sentence suggests that the woman explained it in a calm, unhurried way.

Important: in other contexts, klidně can also mean something like sure, go ahead, or feel free. But that is not the meaning here.

Vysvětlila is the past tense feminine singular form of vysvětlit.

It is feminine because the subject is paní, which refers to a woman.

Compare:

• vysvětlil = he explained
• vysvětlila = she explained

So Paní ... vysvětlila means The lady ... explained.

This is a question of aspect.

• vysvětlila is perfective
• vysvětlovala is imperfective

Here vysvětlila presents the explanation as a completed action: she explained it successfully, and that explanation is viewed as a whole.

Vysvětlovala would sound more like:

• she was explaining
• she kept explaining
• she explained over some period of time

In English, both may sometimes be translated as explained, but Czech makes this difference very clearly.

Because Czech normally separates a subordinate clause with a comma.

The part beginning with kde is an indirect question/subordinate clause:

• kde je náš pokoj
• kde je hlavní vchod

So the comma before them is required in standard Czech punctuation.

Kde je náš pokoj is the most neutral and natural word order.

In Czech, after question words like kde, it is very common for the verb to come before the subject:

• Kde je pokoj?
• Nevím, kde je pokoj.

The version kde náš pokoj je is possible, but it sounds more marked and usually adds emphasis or contrast.

So for normal, neutral speech, kde je náš pokoj is the best choice.

They are both in the nominative singular because they are the subjects of je.

• náš pokoj = our room
• hlavní vchod = the main entrance

A few details:

• pokoj is masculine inanimate singular, so the possessive adjective is náš
• vchod is also masculine inanimate singular
• hlavní is an adjective whose nominative singular form is hlavní

So both phrases are simply the normal subject forms.

Usually yes. The sentence contains two coordinated subordinate clauses:

• kde je náš pokoj
• kde je hlavní vchod

Repeating kde je makes the sentence clear and natural.

A shortened version like kde je náš pokoj a kde hlavní vchod may sometimes occur, but the full version is more standard.

If you said only kde je náš pokoj a hlavní vchod, it would sound wrong, because one singular je cannot naturally cover both pokoj and vchod together.