A word-by-word breakdown is:
So the structure is literally something like:
Natural English: This unit is small.
In Hebrew, the verb to be is usually not stated in the present tense.
So Hebrew says:
But the meaning is:
This is very normal Hebrew.
Compare:
In the past or future, Hebrew does use forms of להיות (to be):
יחידה is a feminine noun. In Hebrew, every noun has grammatical gender, and adjectives and demonstratives have to agree with it.
A very common sign of a feminine noun is the ending ־ה or ־ת, and יחידה ends in ־ה.
Because יחידה is feminine singular, the other words match it:
If the noun were masculine, the forms would change. For example:
Here:
Because הזאת has to agree with the noun יחידה, which is feminine singular.
Hebrew forms of this include:
So:
A native English speaker often expects one word for this, but in Hebrew it changes for gender and number.
In Modern Hebrew, when you say this/that + noun, the noun usually comes first:
So Hebrew often uses:
rather than English-style:
This is one of the most common patterns learners need to get used to.
There is also a more formal/literary pattern with זו:
but היחידה הזאת is the everyday standard way.
In expressions like היחידה הזאת, Hebrew typically uses the noun in its definite form:
Then the demonstrative follows:
So even though English says this unit, Hebrew uses the definite noun plus the demonstrative.
As for הזאת, that is just the normal form of the feminine singular demonstrative in this pattern. You do not analyze it as a separate the + this in the same way you would in English. It is simply the form used in expressions like:
Adjectives in Hebrew must agree with the noun they describe in:
Since יחידה is feminine singular, the adjective must also be feminine singular:
So:
Because here קטנה is a predicate adjective, not an adjective directly attached inside the noun phrase.
Compare these two ideas:
היחידה הזאת קטנה
= This unit is small
Here קטנה is the predicate of the sentence, so it does not take ה־.
היחידה הקטנה הזאת
= this small unit
Here קטנה is directly modifying the noun inside the noun phrase, so it becomes definite too:
This is a very important distinction in Hebrew.
They mean different things structurally:
היחידה הזאת קטנה = This unit is small
היחידה הקטנה הזאת = this small unit
A useful shortcut:
They are closely related, and both can be feminine singular forms meaning this.
In everyday Modern Hebrew:
A more formal or written style may use:
Both can mean this unit, but they are used in different styles and structures.
Very roughly:
For learners, היחידה הזאת is the safest everyday pattern to learn first.
A simple pronunciation guide is:
More carefully:
Stress is usually at the end of each of these words:
If you want a natural rhythm, say it as:
In standard modern usage, הזאת normally means this.
For that, Hebrew usually uses forms like:
So:
In casual speech, context can sometimes blur things a little, but for learning purposes, it is best to remember:
If the noun were masculine singular, both the demonstrative and the adjective would change.
Example:
Compare the two:
The pattern is:
This is a good sentence pair to memorize, because it shows agreement very clearly.