Susjeda je jučer posadila dvije ruže na terasi.

Susjeda means female neighbor / neighbour. Here it is the subject of the sentence, so it is in the nominative singular.

A useful contrast:

• susjed = male neighbor
• susjeda = female neighbor

So the sentence is specifically talking about a woman.

Croatian usually forms the past tense with:

• a present-tense form of biti = to be
• plus the l-participle

So here:

• je = is/has as the auxiliary for he/she/it
• posadila = the past participle form of posaditi

Together, je posadila means planted.

This is one of the most common Croatian past-tense patterns:

• on je posadio = he planted
• ona je posadila = she planted
• oni su posadili = they planted

Because the subject is feminine singular: susjeda.

In Croatian past tense, the participle agrees with the subject in gender and number.

So:

• posadio = masculine singular
• posadila = feminine singular
• posadilo = neuter singular
• posadili / posadile = plural

Since susjeda is a woman, the correct form is posadila.

The dictionary form is posaditi, which means to plant.

This verb is perfective, so it presents the action as completed: she planted them, and the action is seen as finished.

Compare:

• posaditi → completed action
• saditi → ongoing, repeated, or habitual planting

So:

• Susjeda je jučer posadila dvije ruže. = She planted two roses yesterday.
• Susjeda je jučer sadila ruže. = She was planting roses yesterday / planted roses yesterday, with more focus on the process

Because dvije is the form of two used with feminine nouns.

Since ruža is feminine, you say:

• dvije ruže = two roses

Compare:

• dva stola = two tables
• dva sela = two villages
• dvije ruže = two roses

So dva is used with masculine and neuter nouns, while dvije is used with feminine nouns.

The dictionary form is ruža = rose.

Here, ruže is the form used because it is the direct object after the verb posadila. That means it is in the accusative plural.

For this noun, the accusative plural looks the same as the nominative plural:

• singular: ruža
• plural: ruže

So:

• jedna ruža = one rose
• dvije ruže = two roses

Also, after dvije, feminine nouns normally appear in this plural form.

Because na terasi expresses location: the planting happened on the terrace.

With na, Croatian uses different cases depending on meaning:

• na + locative = location, being on/in a place
• na + accusative = movement onto/to a place

So:

• na terasi = on the terrace, at the terrace area
• na terasu = onto the terrace

In this sentence, the neighbor did the planting there, so it is location, which is why Croatian uses the locative singular:

• terasa → na terasi

Croatian word order is fairly flexible, but not completely free.

Jučer means yesterday, and it can appear in different places depending on emphasis. For example:

• Susjeda je jučer posadila dvije ruže na terasi.
• Jučer je susjeda posadila dvije ruže na terasi.
• Susjeda je posadila dvije ruže na terasi jučer.

All are possible, though some sound more natural in certain contexts.

The important thing to notice is that je is a clitic, and clitics usually go in second position in the clause. That is why in the original sentence you get:

• Susjeda je ...

and if you start with Jučer, then:

• Jučer je susjeda ...

Because Croatian has no articles.

So Croatian does not normally have separate words corresponding to English a, an, or the.

That means:

• susjeda can mean a neighbor or the neighbor
• dvije ruže can mean two roses or the two roses, depending on context

The exact meaning is usually understood from the situation, context, or word order.

Yes, very often.

Croatian is a pro-drop language, which means subject pronouns are often omitted when they are clear from context. Since the verb form already shows person, and the participle shows gender, Croatian often does not need an explicit subject.

So if the context already makes it clear who is being talked about, you could say:

• Jučer je posadila dvije ruže na terasi.

That would still mean She planted two roses on the terrace yesterday.

In your sentence, susjeda is included because the speaker wants to name the subject explicitly.

Yes, susjeda je is the normal order here.

The auxiliary je is a clitic, and clitics usually do not stand at the beginning of a clause. They tend to come after the first stressed element.

So:

• Susjeda je jučer posadila... = normal
• Jučer je susjeda posadila... = also normal
• Je susjeda jučer posadila... = generally not normal as a neutral statement

This clitic placement is one of the key word-order rules in Croatian.

A few pronunciation notes:

• susjeda: the j is like English y, so roughly soo-SYE-da
• jučer: j again sounds like y, and č is like ch in church; roughly YOO-cher
• posadila: roughly po-sa-di-la, with clear vowels
• ruže: ž sounds like the s in measure; roughly ROO-zhe
• terasi: roughly te-ra-si

General rule: Croatian spelling is quite phonetic, so words are usually pronounced much as they are written.

It most directly means terrace, but depending on context it can sometimes overlap with what English speakers might call a balcony or an outdoor raised area.

Still, the safest core meaning is:

• terasa = terrace

If you specifically mean a balcony attached to an apartment, balkon is also very common.

So learners should remember:

• terasa = terrace/patio-like outdoor space
• balkon = balcony

This sentence is a good model because it shows several very common Croatian patterns at once:

1. Subject in nominative

   • Susjeda

2. Past tense with auxiliary + participle

   • je posadila

3. Time expression

   • jučer

4. Direct object

   • dvije ruže

5. Place expression with preposition

   • na terasi

You can copy the pattern:

• Majka je jučer kupila dvije knjige u gradu.
• Prijateljica je jutros napravila kavu u kuhinji.
• Učiteljica je prošli tjedan posadila tri biljke u vrtu.

That makes this sentence very useful for practicing everyday Croatian grammar.