Než si něco objednáš, podívej se prosím na jídelní lístek.

Here než means before:

• Než si něco objednáš... = Before you order something...

A useful thing to know is that než can also mean than in comparisons:

• Je vyšší než já. = He is taller than me.

So the exact meaning depends on context.

The verb here is objednat si, which means to order for oneself.

In Czech, many verbs naturally take si or se, and this does not always translate directly into English. So:

• objednat = to order
• objednat si = to order something for yourself

In everyday Czech, when talking about ordering food or drinks in a restaurant, objednat si is very common and natural.

So:

• objednáš alone could sound incomplete in this kind of situation
• si objednáš sounds like normal Czech for you order yourself something

Objednáš is from the perfective verb objednat si. In Czech, perfective verbs use present-tense forms to talk about the future.

So although objednáš looks like a present-tense form, here it means:

• you will order
• or in smoother English in this sentence: before you order

This is very common in Czech:

• až přijde = when he comes / when he has come
• než odejdeš = before you leave

This is a question of aspect.

• objednat si = perfective
  Focuses on the action as a whole, often as a single completed event.
• objednávat si = imperfective
  Focuses on the process, repetition, or ongoing action.

In this sentence, objednáš is used because the speaker means one complete future action:

• Before you order...

If you used objednáváš, it would sound more like you are ordering or you usually order, which does not fit as well here.

Yes, in English this is often translated naturally as something or anything, depending on style:

• Než si něco objednáš...
• literally: Before you order something...
• natural English: Before you order anything...

Czech uses něco in this affirmative subordinate clause very naturally. You do not need a special word equivalent to English anything here.

Podívej se is the singular imperative of podívat se, which means to look or to take a look.

So:

• podívej se = look / take a look

This verb is perfective, so it often suggests a single, complete action:

• Take a look at the menu.

It is a very common polite instruction.

Because the verb is podívat se. The se is part of the verb.

Many Czech verbs are reflexive or fixed with se/si, and you simply have to learn them that way. In this case:

• dívat se na = to look at
• podívat se na = to have a look at / take a look at

So se is not optional here.

They are both short reflexive pronouns, but they do different jobs.

• si is the dative form
• se is the accusative form

In this sentence:

• objednat si něco = to order oneself something
• podívat se na něco = to look at something

For a learner, the most practical approach is often to memorize the full verb pattern:

• objednat si
• podívat se na

rather than trying to translate si and se word for word every time.

Because podívat se commonly goes with na when you say what you are looking at:

• podívat se na něco = to look at something

So:

• na jídelní lístek = at the menu

This is just the normal Czech construction. English says look at, and Czech says podívat se na.

Because after na with podívat se na, Czech uses the accusative case.

The dictionary form is:

• jídelní lístek = menu

And in this case, it happens to look the same in the accusative singular because lístek is a masculine inanimate noun:

• nominative: jídelní lístek
• accusative: jídelní lístek

So the form does not change here, but the case is still accusative.

Literally, it means something like food list:

• jídelní = related to meals/food
• lístek = little лист / slip / list / ticket, depending on context

Together, jídelní lístek means menu.

You may also hear menu, but jídelní lístek is a very common native Czech expression.

Prosím means please, and in Czech it is quite flexible in position.

Here:

• podívej se prosím na jídelní lístek

is a very natural way to say:

• please look at the menu

You could also hear:

• Prosím, podívej se na jídelní lístek.
• Podívej se na jídelní lístek, prosím.

All of these are possible. The version in your sentence sounds natural and polite.

It is informal singular, used with ty.

You can tell from the verb forms:

• objednáš = you (singular informal) will order
• podívej se = imperative for you (singular informal)

If you wanted the formal or plural version, you would say:

• Než si něco objednáte, podívejte se prosím na jídelní lístek.

That can mean:

• Before you order, please look at the menu.
  addressed politely to one person
• or to more than one person

Because Než si něco objednáš is a subordinate clause, and in Czech subordinate clauses are separated by commas.

So the structure is:

• Než si něco objednáš, = subordinate clause
• podívej se prosím na jídelní lístek. = main clause

This comma is required in standard Czech writing.

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

For example, you could also say:

• Podívej se prosím na jídelní lístek, než si něco objednáš.

That means the same thing: Please look at the menu before you order something.

The original version puts the before clause first, which sounds very natural and sets the timing clearly from the start.

By itself, an imperative can sound direct, but here prosím softens it and makes it polite.

So:

• Podívej se na jídelní lístek. = direct, but not necessarily rude
• Podívej se prosím na jídelní lístek. = polite: Please look at the menu

Tone and context matter, but this sentence is perfectly normal and polite in everyday speech.