Ta cvjećarka radi i nedjeljom, pa ću u istu cvjećarnicu otići i prije godišnjice.

They are related words, but they do not mean the same thing:

• cvjećarka = a female florist
• cvjećarnica = a flower shop / florist’s shop

So in this sentence:

• Ta cvjećarka radi... = That florist works...
• u istu cvjećarnicu = to the same flower shop

This is a very common pattern in Croatian: one word refers to a person, while a similar-looking word refers to the place/business.

Ta means that and agrees with cvjećarka, which is:

• feminine
• singular
• nominative

So:

• taj = that (masculine)
• ta = that (feminine)
• to = that (neuter)

Because cvjećarka is feminine, we use ta.

In context, ta cvjećarka often sounds like that florist or that particular florist—someone already known or already mentioned.

Radi is the 3rd person singular present tense of raditi = to work.

So:

• ja radim = I work
• ti radiš = you work
• on/ona radi = he/she works

Since cvjećarka is she grammatically, radi means works.

So:

• Ta cvjećarka radi = That florist works

Nedjeljom is an adverbial use of the instrumental case and means something like:

• on Sundays
• Sundays
• every Sunday / on Sundays in general

So:

• Radi nedjeljom = She works on Sundays

This is different from:

• u nedjelju = on Sunday (one specific Sunday)

So the sentence is talking about a habit / regular schedule, not one single Sunday.

This kind of form is common with days of the week:

• ponedjeljkom = on Mondays
• utorkom = on Tuesdays
• subotom = on Saturdays
• nedjeljom = on Sundays

Here i means also / too / even.

So:

• radi i nedjeljom = works on Sundays too / even works on Sundays

It adds extra information: she does not work only on regular days; she also works on Sundays.

Croatian i is often just and, but in many sentences it also means also/too depending on position and context.

Pa here means something like:

• so
• therefore
• well then
• as a result

It connects the two ideas:

1. That florist works on Sundays too
2. so I’ll go to the same flower shop before the anniversary too

So pa is a natural linking word showing consequence or continuation.

It is very common in spoken and written Croatian.

Croatian future tense is often formed with:

• a short form of htjeti (ću, ćeš, će...)
• plus the infinitive

Here:

• ću = I will
• otići = go / go off / leave

So otići ću or ja ću otići both mean I will go.

In this sentence, ću appears early because it is a clitic. Croatian clitics usually go in the second position of the clause:

• pa ću u istu cvjećarnicu otići...

That word order is very normal in Croatian.

You could also hear:

• Pa otići ću u istu cvjećarnicu...

but the version in your sentence sounds more natural.

Here u means into / to, showing movement toward a place, so it takes the accusative case.

The base noun is:

• cvjećarnica = flower shop

In the accusative singular, it becomes:

• cvjećarnicu

So:

• u cvjećarnicu = to the flower shop / into the flower shop

Because there is movement (I will go to the shop), Croatian uses u + accusative.

Compare:

• u cvjećarnicu = to the flower shop, into the flower shop
• u cvjećarnici = in the flower shop

Because istu has to agree with cvjećarnicu, which is in the accusative singular feminine.

The adjective isti means same. Its form changes depending on gender, number, and case.

Here:

• cvjećarnica is feminine singular
• after u with movement, it becomes accusative: cvjećarnicu
• therefore isti must also become accusative feminine singular: istu

So:

• ista cvjećarnica = the same flower shop (nominative)
• u istu cvjećarnicu = to the same flower shop (accusative)

This i again means also / too / even, not and.

So the speaker is saying something like:

• she works on Sundays, so I’ll also go before the anniversary
• or I’ll even go before the anniversary

It adds another idea to the plan.

Croatian often places i directly before the part it emphasizes. Here it emphasizes prije godišnjice.

The preposition prije means before, and it requires the genitive case.

The base noun is:

• godišnjica = anniversary

Its genitive singular is:

• godišnjice

So:

• prije godišnjice = before the anniversary

This is a very common pattern:

• prije ručka = before lunch
• prije sastanka = before the meeting
• prije škole = before school

So after prije, expect the genitive.

Yes, otići often has the sense of go away / leave, but in many contexts it is also a normal way to say go somewhere.

Here:

• otići u istu cvjećarnicu = go to the same flower shop

The destination is stated, so the meaning is very natural.

Croatian often uses:

• ići = to go
• otići = to go off, leave, go somewhere

In this sentence, otići can sound a bit more like make a trip there / go over there, but in English the natural translation is usually just go.

Croatian word order is fairly flexible, but not random.

This sentence:

• Ta cvjećarka radi i nedjeljom, pa ću u istu cvjećarnicu otići i prije godišnjice.

is natural because:

• ću is in second position in its clause
• i is placed near what it emphasizes
• the destination u istu cvjećarnicu comes before otići, which is very common

You may also hear variations such as:

• Ta cvjećarka radi i nedjeljom, pa ću i prije godišnjice otići u istu cvjećarnicu.

That version shifts the emphasis a little more toward before the anniversary.

So the word order can change, but the placement of clitics like ću is especially important.

Yes: it helps distinguish between the person and the shop.

The first part talks about the florist:

• Ta cvjećarka radi...

The second part talks about the flower shop as the destination:

• u istu cvjećarnicu

This is useful because in English we sometimes say I’ll go to the same florist, where florist can mean either the person or the business. Croatian is more explicit here:

• cvjećarka = the woman
• cvjećarnica = the shop

So the sentence clearly says: because that florist is working, I’ll go to that same shop.