هذه شتلة.

Because شتلة is a feminine singular noun, and the demonstrative must agree with it.

• هذا = this for masculine singular
• هذه = this for feminine singular

Since شتلة ends in ة (taa marbuuTa), it is feminine, so هذه is the correct form.

هذه means this for a feminine singular noun.

It is usually pronounced haadhihi.

A rough pronunciation guide:

• haa = long aa
• dh = like the th in this
• hi = short hi

So: haa-dhi-hi

In Arabic, the present tense verb to be is usually not stated in simple sentences like this.

So:

• هذه شتلة literally looks like this seedling
• but it means This is a seedling

This is completely normal in Arabic nominal sentences.

If you wanted the past tense, then Arabic would use a verb, for example:

• كانت هذه شتلة = This was a seedling

It is a nominal sentence in Arabic.

A simple way to understand it is:

• هذه = the subject-like part
• شتلة = the predicate / description

So the structure is basically:

• هذه = this
• شتلة = a seedling

Together: This is a seedling.

In traditional grammar:

• هذه is the mubtadaʾ
• شتلة is the khabar

Because here the sentence means This is a seedling, not This is the seedling.

Compare:

• هذه شتلة = This is a seedling
• هذه الشتلة = This is the seedling or this seedling, depending on context

So the lack of ال makes شتلة indefinite.

This is a very important distinction in Arabic:

• هذا كتاب = This is a book
• هذا الكتاب = This book / This is the book

Normally, هذه شتلة is understood as This is a seedling.

If you want this seedling as a noun phrase, the usual form is:

• هذه الشتلة

That is because Arabic normally uses:

• demonstrative + definite noun for this/that + noun

So:

• هذه شتلة = a full sentence
• هذه الشتلة = a noun phrase

The main clue is the ending ة.

Many Arabic nouns ending in ة are feminine, and شتلة is one of them.

So learners often use this as a helpful rule:

• if a noun ends in ة, it is often feminine

That is why it takes هذه rather than هذا.

It is usually pronounced shatlah in pause.

Breakdown:

• ش = sh
• ت = t
• ل = l
• final ة = usually sounds like -ah when stopping

So: shat-lah

In fully vowelled formal grammar, it can be shatlatun when case endings are pronounced.

Because ة (taa marbuuTa) is usually pronounced:

• -ah / -a when pausing
• -t when followed by a grammatical ending or in certain connected forms

So in normal citation or at the end of the sentence:

• شتلة → shatlah

But in fully formal pronunciation with case endings:

• شتلةٌ → shatlatun

This is a very common feature of Arabic pronunciation.

In fully vocalized formal Arabic, yes, the indefinite predicate would normally be:

• هذه شتلةٌ

The ـٌ shows that شتلة is indefinite nominative.

However, in normal unvowelled writing, Arabic usually leaves short vowels and tanwiin unwritten, so you simply see:

• هذه شتلة

That is completely normal.

A fully vowelled version is:

• هٰذِهِ شَتْلَةٌ

This shows:

• هٰذِهِ = feminine singular this
• شَتْلَةٌ = a seedling, with tanwiin

In everyday printed Arabic, you will usually see it without most of these marks:

• هذه شتلة

You would use هذا instead of هذه.

For example:

• هذا كتاب = This is a book

So the pattern is:

• هذه + feminine singular noun
• هذا + masculine singular noun

That agreement is one of the first things Arabic learners need to get used to.

Yes. This is a very normal pattern.

Arabic often expresses This is X with:

• demonstrative + noun

Examples:

• هذا بيت = This is a house
• هذه سيارة = This is a car
• هذه شتلة = This is a seedling

So the word order here is natural and common.