U subotu planiramo izlet i piknik.

In Serbian, u + accusative is the normal way to say on with days of the week:

• u subotu = on Saturday
• u ponedeljak = on Monday
• u nedelju = on Sunday

So u subotu is the standard expression here.

Using na subotu would not sound natural in this meaning. And just subota by itself would not work as a normal time expression in this sentence.

Because after u in this time expression, Serbian uses the accusative case.

• nominative: subota
• accusative: subotu

So:

• Subota je lep dan. = Saturday is a nice day.
• U subotu planiramo izlet. = On Saturday we’re planning an outing.

This is a very common pattern with days of the week.

Planiramo is the 1st person plural present tense of planirati = to plan.

So planiramo means:

• we plan
• we are planning

In this sentence, because there is a clear future time expression (u subotu), it is naturally understood as something future-oriented:

• On Saturday we’re planning an outing and a picnic
• or more naturally in English: We’re planning an outing and a picnic for Saturday / on Saturday

Serbian often uses the present tense this way when the time is clear from context.

Because Serbian very often uses the present tense for planned or scheduled future actions, especially when a time expression makes the meaning clear.

Here, u subotu already tells you when it will happen, so planiramo sounds natural.

A future form is also possible in some contexts, but the present is very common for plans and arrangements.

Yes, they are the direct objects of planiramo, so they are in the accusative case.

But both izlet and piknik are masculine inanimate nouns, and for many nouns of that type, the accusative singular looks the same as the nominative singular.

So:

• nominative: izlet

• accusative: izlet

• nominative: piknik
• accusative: piknik

That is why they appear unchanged.

Yes:

• izlet = an outing, excursion, day trip
• piknik = picnic

So izlet suggests going somewhere, while piknik refers more specifically to eating outdoors.

Together, izlet i piknik suggests a trip/outing that includes a picnic.

Because Serbian has no articles.

English distinguishes between:

• a picnic
• the picnic

Serbian does not use separate words like a/an/the. The meaning is understood from context.

So:

• izlet can mean an outing or the outing
• piknik can mean a picnic or the picnic

The sentence context tells you how specific the speaker is being.

Yes. Serbian word order is more flexible than English word order.

For example, these are all possible depending on emphasis:

• U subotu planiramo izlet i piknik.
• Planiramo izlet i piknik u subotu.
• Izlet i piknik planiramo u subotu.

The original version puts early focus on u subotu = on Saturday.

English word order is usually more fixed, but Serbian can move things around more easily.

Yes. I means and.

So:

• izlet i piknik = outing and picnic

It is used just like English and to connect two nouns.

It usually means on Saturday, but in real conversation it often gets understood as this Saturday if the context is about an upcoming plan.

Serbian often relies on context rather than extra words.

If needed, speakers can be more specific, but u subotu by itself is very common and natural.

The dictionary forms are:

• planirati = to plan
• subota = Saturday
• izlet = outing / excursion
• piknik = picnic

So the sentence contains:

• u subotu → subota in the accusative after u
• planiramo → from planirati
• izlet and piknik → object forms that happen to look the same as the basic form

Piknik is a loanword, ultimately corresponding to English picnic.

It is fully used in Serbian and behaves like a normal masculine noun:

• piknik
• piknika
• pikniku, etc.

So even though it is borrowed, learners should treat it as a regular Serbian noun in everyday use.

A very literal breakdown is:

• U subotu = on Saturday
• planiramo = we plan / we are planning
• izlet i piknik = an outing and a picnic

So the structure is basically:

On Saturday, we are planning an outing and a picnic.

Depending on context, a more natural English translation might also be:

We’re planning an outing and a picnic for Saturday.