Daj znać, czy możesz wpaść i wyskoczyć na kawę.

Yes — daj znać is a very common expression meaning let me know.

Literally, it comes from dać (to give) + znać (historically connected with knowing/noticing), but in modern everyday Polish you should learn dać znać as a whole phrase.

Examples:

• Daj znać, kiedy będziesz. = Let me know when you’ll be here.
• Daj znać, czy masz czas. = Let me know if/whether you have time.

It sounds natural and conversational.

Daj is the imperative form of dać for one person in the informal ty form.

So:

• daj znać = let me know (to one person, informal)
• dajcie znać = let me know (to more than one person, informal plural)

Because the sentence uses daj and możesz, it is clearly addressed to one person you speak to informally.

Yes, it is informal.

The clues are:

• daj = imperative for informal singular
• możesz = you can in the informal ty form

More polite versions could be:

• Proszę dać znać, czy może Pan/Pani wpaść i wyskoczyć na kawę.
• Niech Pan/Pani da znać, czy może Pan/Pani wpaść i wyskoczyć na kawę.

In everyday speech, daj znać is very common among friends, family, coworkers on informal terms, etc.

Here czy introduces an indirect yes/no question. It means whether or if.

So:

• Daj znać, czy możesz... = Let me know whether/if you can...

This is not the same kind of if as a condition like if it rains. In Polish:

• czy = whether / if in an indirect question
• jeśli / jeżeli = if in a condition

Compare:

• Nie wiem, czy przyjdzie. = I don’t know whether he’ll come.
• Jeśli przyjdzie, porozmawiamy. = If he comes, we’ll talk.

Because Polish usually drops subject pronouns when they are clear from the verb form.

• możesz already means you can
• the ending -sz tells you it is 2nd person singular

So ty możesz is possible, but usually only used for:

• emphasis
• contrast
• clarification

For example:

• Czy możesz wpaść? = neutral
• Czy ty możesz wpaść? = more emphatic, like can you, specifically?

Because after móc (can / to be able to), Polish normally uses an infinitive.

So:

• możesz wpaść = you can drop by
• możesz wyskoczyć = you can go out / pop out

This is similar to English:

• can come
• can go
• can help

You do not conjugate the second verb here; only możesz is conjugated.

They are perfective because the sentence is talking about single, complete actions:

• one act of dropping by
• one act of going out for coffee

With modal verbs like móc, Polish still chooses aspect based on meaning. Here the speaker means something like:

• Can you come by once
• Can you go out for coffee

So perfective verbs are natural:

• wpaść
• wyskoczyć

If you used imperfective forms, the meaning would shift toward a more general or ongoing idea, which is not the point here.

Here wpaść means to drop by, to pop in, or to come over briefly/casually.

It is a very colloquial, friendly verb. It often suggests:

• the visit is not very formal
• the visit may be short
• the tone is relaxed or spontaneous

Compare:

• przyjść = to come (more neutral)
• odwiedzić = to visit (more deliberate, often less casual)
• wpaść = to pop in / drop by (casual)

So wpaść is a good match for friendly invitations.

Yes — wpaść can have several meanings depending on context.

It can mean things like:

• fall into
• burst in
• run into
• drop by

This is very common with Polish prefixed verbs: one form can develop several related meanings.

In this sentence, because the context is social and includes na kawę, the meaning is clearly drop by / come over casually.

Wyskoczyć na kawę is a casual expression meaning to go out for a coffee, to grab a coffee, or to pop out for coffee.

Literally, wyskoczyć is something like jump out, but in everyday Polish it often means:

• go out quickly
• pop out somewhere
• do something spontaneous or brief

So wyskoczyć na kawę has a light, informal feel. It suggests:

• not a formal meeting
• probably not very long
• something easy and casual

Similar expressions:

• wyskoczyć na piwo = go out for a beer
• wyskoczyć na lunch = go out for lunch
• wyskoczyć na spacer = go out for a walk

Because na here takes the accusative case, and kawa in the accusative singular becomes kawę.

So:

• nominative: kawa
• accusative: kawę

This pattern is very common after verbs of going somewhere for a purpose:

• iść na kawę = go for coffee
• wyskoczyć na lunch = go out for lunch
• pójść na spacer = go for a walk
• wpaść na obiad = come by for dinner

So na kawę is exactly what you would expect.

Because both infinitives depend on the same verb możesz.

Structure:

• czy możesz [wpaść] i [wyskoczyć na kawę]

This is just like English:

• Can you drop by and go for coffee?

There is no need to repeat możesz before the second verb unless you want unusual emphasis.

It is understandable and colloquial, but it is worth noticing that the two verbs point in slightly different directions:

• wpaść = come by / drop in
• wyskoczyć na kawę = go out for coffee

So together, it can suggest:

• drop by and then go out for coffee
• or more loosely, meet up casually for coffee

Depending on the exact situation, a Polish speaker might also say:

• Daj znać, czy możesz wpaść na kawę. = Let me know if you can come by for coffee.
• Daj znać, czy możesz wyskoczyć na kawę. = Let me know if you can go out for coffee.

So the original sentence works, but the context decides whether both verbs are really needed.

Sometimes, but not always.

• daj znać = let me know
• powiedz mi = tell me

Daj znać is often more natural when you want someone to inform you later, after checking or deciding something.

Compare:

• Daj znać, czy możesz przyjść. = Let me know if you can come.
• Powiedz mi, czy możesz przyjść. = Tell me if you can come.

The second one is grammatically fine, but daj znać sounds more idiomatic and natural in this kind of invitation/planning context.