Learn Hardcore Japanese: kore ha watasi no hon desu.

これ means this (a demonstrative pronoun).
は is the topic‐marker particle (pronounced wa).
私 (わたし) means I or me (the speaker).
の is the possessive/genitive particle, equivalent to ’s or of.
本 (ほん) means book.
です is the polite copula, roughly is in English.

Why is the particle は written as ha but pronounced wa?

Historically, は was pronounced wa when used as a topic marker. Modern Japanese keeps the spelling は but reads it wa in that role. When は appears in other words (like はな “flower”), it’s still ha.

What’s the difference between これは私の本です and これが私の本です?

Using は (これは) introduces this as the topic:
“As for this, it’s my book.”
Using が (これが) focuses/emphasizes this as the subject:
“This (specifically) is my book (and not something else).”
Both are correct, but が can feel more definitive or contrastive.

Why is の used between 私 and 本? Could I drop it?

The particle の connects the possessor (私) to what is possessed (本), like my book. Without の, the relationship is unclear. You cannot say 私は本です to mean this is my book—that would mean “I am a book.”

What does です actually do? Is it a verb?

です is the polite copula. It isn’t a verb like “to put” or “to do”; it simply links the subject/topic to a noun or adjective, functioning like “is/am/are” in English. In casual speech you’d use だ instead of です.

Why aren’t there any articles like “a” or “the” in Japanese?

Japanese has no direct equivalents of a or the. Definiteness or indefiniteness is understood from context or added words (e.g. この本 “this book,” ある本 “a certain book”). Here, これ (“this”) makes it clear which book is meant.

How do I know when to use これ, それ, or あれ?

Use これ (“this”) for something near you (the speaker).
Use それ (“that”) for something near the listener.
Use あれ (“that over there”) for something distant from both speaker and listener.

Why are there spaces between the words in this example? I thought Japanese doesn’t use spaces.

Correct—standard Japanese text doesn’t use spaces. Here we’ve inserted spaces to help learners see each particle and word. In real writing or speech, you’d write it as これは私の本です without spaces.

Can I say これ私の本です by dropping は in casual speech?

While you’ll hear some particles dropped in very informal conversation, dropping は here would sound unnatural or incomplete. It’s best to keep は: これは私の本です.