Když je lavička prázdná, moje babička tam ráda sedí.

Here když means when, and more specifically whenever in a general sense.

So the sentence is talking about a repeated situation:

• Když je lavička prázdná... = When/Whenever the bench is empty...

In everyday Czech, když can sometimes overlap a bit with English if, especially in casual speech, but in this sentence when/whenever is the most natural understanding.

Je is the 3rd person singular present tense of být (to be).

So:

• lavička je prázdná = the bench is empty

Czech often uses to be the same way English does with adjectives:

• je prázdná = is empty
• je velká = is big
• je stará = is old

Because prázdná has to agree with lavička.

• lavička is a feminine singular noun
• adjectives describing it must also be feminine singular

So:

• masculine: prázdný
• feminine: prázdná
• neuter: prázdné

Examples:

• prázdný stůl = empty table
• prázdná lavička = empty bench
• prázdné křeslo = empty armchair

It is historically a diminutive form, and Czech uses it as the normal everyday word for bench.

It comes from lavice, but in modern usage:

• lavička = the usual word for a bench, especially in a park
• lavice often means a school desk/bench, a pew, or a longer bench depending on context

So in this sentence, lavička is simply the natural word for bench.

Yes, both are possible.

• moje babička
• má babička

Both mean my grandmother.

In many contexts, moje sounds a bit more neutral and conversational, while má can sometimes sound a little more literary, emphatic, or compact. But both are perfectly normal Czech.

A learner should mainly know that Czech has two common forms for my:

• můj
• moje / má depending on gender, case, and style

Here babička is feminine singular, so moje and má are both acceptable.

Because Czech often leaves out subject pronouns when they are clear from context.

In English, you usually need:

• my grandmother likes sitting there

But in Czech, once the subject is stated as moje babička, you do not need an extra ona (she).

In fact, adding ona would usually sound emphatic:

• moje babička tam ráda sedí = neutral
• moje babička, ta tam ráda sedí / ona tam ráda sedí = more contrastive or emphatic

Because rád changes according to the gender of the person who likes doing something.

Here the subject is moje babička, which is feminine, so:

• masculine speaker/person: rád
• feminine speaker/person: ráda

So:

• Babička tam ráda sedí. = Grandma likes sitting there.
• Dědeček tam rád sedí. = Grandpa likes sitting there.

This is a very common Czech pattern:

• mám rád / ráda + verb
• rád / ráda + verb

It means likes sitting or likes to sit.

Czech often uses rád / ráda with a verb to express liking an activity:

• ráda sedí = she likes sitting / she likes to sit
• rád čte = he likes reading
• ráda chodí ven = she likes going out

So the structure is not literally a direct equivalent of English likes, but functionally it works that way.

It can cover both ideas, depending on context.

Sedět means to sit or to be sitting.
So sedí can mean:

• sits
• is sitting
• in this sentence, more naturally: likes to sit

Because this sentence describes a habit or usual situation, sedí is best understood as a habitual present:

• my grandmother likes sitting there

Tam means there.

In this sentence it refers back to the bench:

• tam ráda sedí = she likes sitting there

Even though English might say sit on it or just sit there, Czech very naturally uses tam to point back to the place.

Without tam, the sentence would still be grammatical:

• moje babička ráda sedí

But that would just mean my grandmother likes sitting, without clearly connecting it to the bench.

Yes, Czech word order is flexible, but different orders sound more or less natural depending on emphasis.

The given order is very natural:

• moje babička tam ráda sedí

It presents the information smoothly:

1. subject: moje babička
2. place reference: tam
3. attitude: ráda
4. verb: sedí

Other orders are possible, for example:

• Moje babička ráda sedí tam.
• Tam moje babička ráda sedí.
• Ráda tam moje babička sedí.

But these would shift emphasis. Czech often moves words around to highlight what is new, contrasted, or especially important.

Because Když je lavička prázdná is a subordinate clause, and Czech normally separates subordinate clauses with a comma.

So:

• Když je lavička prázdná, moje babička tam ráda sedí.

This is standard Czech punctuation.

English also often uses a comma after an introductory clause:

• When the bench is empty, my grandmother likes sitting there.

Yes. In Czech, prázdný / prázdná / prázdné can be used not only for containers, but also for places, seats, rooms, streets, etc.

So:

• prázdná lavička = an unoccupied bench
• prázdný pokoj = an empty room
• prázdná židle = an empty chair
• ulice je prázdná = the street is empty

So here it naturally means the bench has no one sitting on it.

Yes, and that is probably the most natural interpretation.

The present tense in both parts suggests a general truth or habit:

• Whenever the bench is empty, my grandmother likes to sit there.

So it is not just about one specific occasion. It sounds like something she usually does.

If Czech wanted to make it clearly about one specific moment, the context would normally help, or the sentence might be phrased differently.

A rough guide for English speakers:

• k as in skin
• dž like the j in jam
• y is a short Czech vowel that does not sound exactly like English ee or i, but learners often approximate it with a short i
• ž sounds like the s in measure

In practice, learners often remember když approximately as gdyzh or kdyzh, though that is only an approximation.

The most important thing is that the final ž is voiced, like measure, not like sh.

Yes, several very common Czech patterns appear here:

1. když introduces a when/whenever clause
2. adjectives agree with nouns:
   • lavička → prázdná
3. Czech often drops subject pronouns
4. rád / ráda + verb is a very common way to say like doing
5. tam often refers naturally to a place already mentioned
6. Czech word order is flexible, but the given order is very natural

So this one sentence is a good example of several core Czech habits at once.