Metu la ŝraŭbon en la bremsblokon.

Metu is the -u verb form, which Esperanto uses for commands, requests, instructions, and similar ideas.

So:

• meti = the basic verb
• metu = put! / place!

In a sentence like this, metu is basically telling someone to do something. The subject is usually understood as you, so Esperanto often does not need to say vi.

• Metu la ŝraŭbon... = Put the screw...
• Vi metu la ŝraŭbon... = also possible, but usually less natural unless you want emphasis

The -n marks the direct object.

Here, the screw is the thing being put, so ŝraŭbo becomes ŝraŭbon.

Compare:

• La ŝraŭbo estas sur la tablo. = The screw is on the table.
• Metu la ŝraŭbon sur la tablon. = Put the screw onto the table.

In Esperanto, this accusative -n is very common and is one of the first endings learners need to get used to.

Because after some prepositions, Esperanto uses -n to show movement toward a place, not just location.

So:

• en la bremsbloko = in the brake block, inside it, with no idea of movement
• en la bremsblokon = into the brake block, showing movement into it

That is why this sentence has two nouns with -n:

• la ŝraŭbon = the direct object
• la bremsblokon = the destination of movement after en

This is a very important Esperanto pattern:

• sur la tablo = on the table
• sur la tablon = onto the table

La is the Esperanto word for the.

It does not change for:

• singular or plural
• masculine or feminine
• case

So la always stays la.

It appears twice because both nouns are definite:

• la ŝraŭbon = the screw
• la bremsblokon = the brake block

Also, Esperanto has no indefinite article. So there is no separate word for a/an. If you wanted a less specific meaning, you might simply leave out la.

Yes. Bremsbloko is a compound.

It is built from:

• brems- = brake-related
• bloko = block

So bremsbloko means a kind of block connected with braking: a brake block.

Esperanto forms compounds very freely. Usually the last part is the main thing, and the earlier part modifies it.

Examples of the same pattern:

• akvobotelo = water bottle
• lignotablo = wooden table
• manlibro = handbook

So bremsbloko is literally a brake-block.

Yes. Esperanto word order is fairly flexible, because endings show grammatical roles.

The most neutral order here is:

• Metu la ŝraŭbon en la bremsblokon.

But other orders are possible, especially for emphasis:

• En la bremsblokon metu la ŝraŭbon.
• La ŝraŭbon metu en la bremsblokon.

Because of the -n endings, the listener can still tell what is the object and what is the destination.

That said, learners should usually start with the more neutral order: verb + object + place/direction.

Because Esperanto often expresses that idea by combining:

• a preposition such as en
• with the accusative -n for direction

So en + accusative often equals English into.

Examples:

• Mi estas en la domo. = I am in the house.
• Mi iras en la domon. = I am going into the house.

So in your sentence, en la bremsblokon naturally carries the idea of into the brake block.

A few parts may look unfamiliar to an English speaker:

• ŝ is pronounced like English sh
• aŭ sounds roughly like ow in cow
• b is always a clear b
• o is a pure o
• n is pronounced normally

So ŝraŭbo is approximately SHROW-bo, with the stress on the second-to-last syllable.

That stress rule is regular in Esperanto: stress always falls on the penultimate syllable.

So:

• ME-tu
• ŜRAŬ-bo
• brems-BLO-ko

In this kind of sentence, the -u form usually implies you automatically.

So Metu ... means something like:

• Put ...
• Please put ...
• Set ...

Esperanto often leaves the subject unspoken in commands, just like English often does.

If needed, you can make it explicit:

• Vi metu la ŝraŭbon en la bremsblokon.

But normally that is unnecessary unless you want contrast or emphasis.

Also, the -u form can be used with other persons:

• Li metu ĝin tie. = Let him put it there.
• Ni metu ĝin ĉi tien. = Let’s put it here.

So -u is broader than just the English imperative, though in this sentence it functions as a direct instruction.