Pak breekbare glazen pas morgen uit.

Because uitpakken is a separable verb.

The full verb is uitpakken = to unpack. In a main clause or an imperative, Dutch splits that verb:

• Pak ... uit.
• Ik pak ... uit.

So pak goes near the front, and uit moves to the end.

If you use the infinitive, the parts stay together:

• Ik wil de glazen morgen uitpakken.

Here pas means not until or only in time expressions.

So pas morgen means:

• not until tomorrow
• only tomorrow

It adds the idea of delay: wait until tomorrow.

Without pas, morgen would just mean tomorrow, but not necessarily with that strong not before then feeling.

Because in Dutch, pas already carries that meaning in this kind of sentence.

So:

• pas morgen = not until tomorrow

You do not normally need niet as well.

If you added niet carelessly, the sentence could become ungrammatical or change meaning.

Pak is the imperative form of pakken.

Dutch often makes a direct command with the verb stem:

• pakken → pak
• lopen → loop
• kijken → kijk

So Pak ... uit means Unpack ...

This sounds like a normal instruction or command. If you want to make it softer, Dutch often uses things like:

• alsjeblieft
• kun je ...
• zou je ...

Because Dutch, like English, can use a bare plural for a nonspecific group.

So breekbare glazen means something like:

• fragile glasses
• any fragile glasses
• fragile glassware items in a general sense

If you mean a specific set of glasses, you would usually add an article:

• Pak de breekbare glazen pas morgen uit.

That means the fragile glasses, not just fragile glasses in general.

Because Dutch adjectives usually take -e when they come before a plural noun.

So:

• breekbaar = base form
• breekbare glazen = fragile glasses

Compare:

• Het glas is breekbaar.
  Here the adjective stands separately after the verb, so it stays breekbaar.

• breekbare glazen
  Here it comes directly before the noun, so it takes -e.

Here glazen is the plural noun of glas and means glasses as drinking glasses.

It does not mean eyeglasses. For eyeglasses, Dutch normally uses brillen.

Also, even though glazen can look like an adjective meaning made of glass, that is not what is happening here. In this sentence, glazen is the noun being described by breekbare.

Yes. Both pas morgen and morgen pas are possible.

The difference is mostly one of emphasis and rhythm:

• pas morgen keeps pas tightly linked to the time expression
• morgen pas can sound a bit more emphatic in speech

So both can work, but the given sentence is a perfectly natural way to say it.

Yes. It is an imperative, so it sounds like a direct instruction.

That is completely normal in contexts like:

• moving house
• packing/unpacking instructions
• labels
• workplace directions
• family instructions

If you want to sound softer, you could say something like:

• Kun je de breekbare glazen pas morgen uitpakken?
• Pak de breekbare glazen pas morgen uit, alsjeblieft.