Η πένσα είναι στο συρτάρι δίπλα στο κατσαβίδι.

Η is the definite article meaning the. It agrees with πένσα in gender, number, and case.

• η = feminine singular nominative
• πένσα is a feminine singular noun
• Together, η πένσα = the pliers / the pincers

Greek uses articles very regularly, often more regularly than English.

In this sentence, πένσα is singular in Greek.

That is one of the things that can feel strange to English speakers: some tools that are plural in English are treated as singular nouns in Greek.

So:

• Η πένσα είναι... = literally The pliers is... if translated word-for-word
• but in natural English we say The pliers are...

So you should learn πένσα as a normal singular Greek noun, even though its English equivalent is usually plural.

Είναι means is here. It is the present tense form of to be.

A useful thing to know is that είναι is used for:

• he is
• she is
• it is
• they are

So Greek does not change this form depending on whether the subject is he/she/it or they.

In this sentence:

• Η πένσα είναι... = The pliers is / are...
• naturally in English: The pliers are...

Στο is a contraction of:

• σε = in / at / on / to
• το = the

So:

• σε + το = στο

In this sentence:

• στο συρτάρι = in the drawer

Greek very commonly combines σε with the article:

• στο = in/at/on/to the (neuter singular or masculine accusative in some patterns)
• στη = in/at/on/to the (feminine singular)
• στην = same, before vowels or depending on style/spelling
• στον = to the / in the (masculine singular)

Because Greek σε covers several meanings that English often separates:

• in
• at
• on
• sometimes to

So σε is a broad preposition, and the exact English translation depends on context.

Examples:

• στο συρτάρι = in the drawer
• στο τραπέζι = on the table
• στο σπίτι = at home / in the house

So you should not expect a one-to-one match between Greek σε and English in.

It actually is in the accusative case, because σε takes the accusative. But συρτάρι is a neuter noun, and for many neuter nouns, the nominative and accusative look the same.

So:

• nominative: το συρτάρι
• accusative: το συρτάρι

No visible change appears, even though the case has changed grammatically.

Both συρτάρι and κατσαβίδι are neuter nouns.

You can tell from the article:

• το συρτάρι = the drawer
• το κατσαβίδι = the screwdriver

In the sentence, they appear as:

• στο συρτάρι
• στο κατσαβίδι

because στο = σε + το.

Δίπλα means next to / beside.

It often works with a following phrase introduced by σε:

• δίπλα σε... = next to...
• δίπλα στο κατσαβίδι = next to the screwdriver

So the structure is:

• δίπλα = next to / beside
• στο κατσαβίδι = the thing it is next to

Together:

• δίπλα στο κατσαβίδι = next to the screwdriver

Because δίπλα is followed by a phrase with σε.

Underlying structure:

• δίπλα σε το κατσαβίδι

But Greek contracts that to:

• δίπλα στο κατσαβίδι

So this second στο is not random; it is part of the expression δίπλα σε....

It is in the accusative, because it follows σε as part of δίπλα στο....

But again, since κατσαβίδι is neuter, the form looks the same in nominative and accusative:

• nominative: το κατσαβίδι
• accusative: το κατσαβίδι

So the article and preposition show the grammar more clearly than the noun ending does.

Greek word order is more flexible than English word order.

The neutral order here is:

• Η πένσα είναι στο συρτάρι δίπλα στο κατσαβίδι.

But other orders are possible depending on emphasis, for example:

• Στο συρτάρι δίπλα στο κατσαβίδι είναι η πένσα.
• Η πένσα είναι δίπλα στο κατσαβίδι, στο συρτάρι.

English usually depends more heavily on word order, while Greek can move elements around more freely. The most natural version, though, is the one you were given.

The accent marks show which syllable is stressed.

In this sentence, the main stresses are:

• Η πένσα → stress on πέν-
• είναι → stress on εί-
• συρτάρι → stress on -τά-
• δίπλα → stress on δί-
• κατσαβίδι → stress on -βί-

A rough pronunciation guide:

• η πένσα ≈ ee PEN-sa
• είναι ≈ EE-ne
• στο συρτάρι ≈ sto seer-TA-ree
• δίπλα ≈ DEE-pla
• στο κατσαβίδι ≈ sto kat-sa-VEE-thee

In Modern Greek, the accent mark is important because stress is phonemic and can distinguish words.

Usually, no, not in a sentence like this.

Greek normally uses the definite article where English might also use the, and often Greek is less willing than English to omit it.

So:

• Η πένσα = the pliers
• στο συρτάρι = in the drawer
• στο κατσαβίδι = next to the screwdriver

If you remove the articles, the sentence would sound unnatural or would change meaning.

You decide from the context.

Greek σε is broader than English prepositions, so the same Greek form can correspond to different English choices:

• στο συρτάρι → in the drawer
• στο τραπέζι → on the table
• στο γραφείο → at the office / in the office

So when translating, you should not translate στο mechanically every time. You should ask what sounds natural in English in that context.