קניתי ארבעה כרטיסים.

A common pronunciation is kaníti arba'á kartisím.

A rough syllable breakdown:

• קניתי = ka-NI-ti
• ארבעה = ar-ba-A
• כרטיסים = kar-ti-SIM

Hebrew is usually written without vowel marks in everyday text, so learners often have to learn the vowels from familiarity and context.

קניתי means I bought.

It comes from the verb לקנות / קנה, meaning to buy / he bought.
The ending -תי is the regular 1st person singular past ending, so the whole word already includes I.

So:

• קנה = he bought
• קניתי = I bought

No. In Hebrew, subject pronouns are often omitted when the verb already makes the subject clear.

Since קניתי already means I bought, you do not need אני.

• קניתי ארבעה כרטיסים = neutral, natural
• אני קניתי ארבעה כרטיסים = I bought four tickets, with extra emphasis or contrast

Yes. קניתי is the same for both male and female speakers.

In the 1st person singular past, Hebrew does not distinguish gender:

• a man can say קניתי
• a woman can also say קניתי

That is often good news for learners, because some other Hebrew forms do change by gender, but this one does not.

Because כרטיס is a masculine noun, and the number has to match it.

With numbers 3–10, Hebrew uses different forms for masculine and feminine nouns:

• masculine: ארבעה
• feminine: ארבע

Since כרטיס is masculine, you say:

• ארבעה כרטיסים

If the noun were feminine, you would use ארבע instead:

• ארבע מחברות = four notebooks

כרטיסים means tickets.

The singular is:

• כרטיס = ticket

The ending -ים is the common masculine plural ending in Hebrew, so:

• כרטיס = ticket
• כרטיסים = tickets

This also helps explain why the number is ארבעה: the noun is masculine.

Because את is used before a definite direct object, and ארבעה כרטיסים is indefinite: four tickets, not the four tickets.

So:

• קניתי ארבעה כרטיסים = I bought four tickets

But if you meant the four tickets, you would use את:

• קניתי את ארבעת הכרטיסים

That form is more advanced, but the basic rule is simple:
use את with definite direct objects, not indefinite ones.

Because the subject is not stated separately. Since קניתי already means I bought, the sentence can naturally begin with the verb.

So the structure is basically:

• קניתי = I bought
• ארבעה כרטיסים = four tickets

This is a very normal Hebrew sentence.

Yes, but the emphasis may change.

The most neutral version here is:

• קניתי ארבעה כרטיסים

You could also say:

• אני קניתי ארבעה כרטיסים = emphasizes I
• ארבעה כרטיסים קניתי = emphasizes four tickets

So the given sentence is the most straightforward, neutral way to say it.