kyou wa watashi no tanjoubi desu kara, keeki o tabemasu.

Today is my birthday, so I will eat cake.

Breakdown of kyou wa watashi no tanjoubi desu kara, keeki o tabemasu.

• は: topic particle
• です: to be
• 私わたし: I
• を: direct object particle

Questions & Answers about kyou wa watashi no tanjoubi desu kara, keeki o tabemasu.

What does the particle は after 今日 do?

は marks 今日 as the topic of the sentence, signaling that what follows is a comment about today (“as for today…”).

What’s the function of の in 私の誕生日?

の is the possessive/genitive particle linking 私 to 誕生日, producing 私の誕生日 meaning my birthday.

Why is there です after 誕生日?

Because 誕生日 is a noun, and in polite Japanese you use the copula です to say “is.” So 今日は私の誕生日です means “Today is my birthday.”

How does から work in this sentence?

から attaches to the preceding clause as ～ですから (“because …”), giving the reason for the main action that follows.

Why is it ですから rather than だから?

In polite speech we use ですから, the polite counterpart to casual だから. If you switch to casual you could say 誕生日だから、ケーキを食べる.

Why is written in katakana?