Morgens packe ich in die Wickeltasche nicht nur ein Fläschchen, sondern auch zwei Windeln und eine Decke.

Here Morgens means in the mornings or every morning.

It is capitalized because it is the first word of the sentence. In the middle of a sentence, it would normally be morgens.

This morgens is an adverb, not a noun. Compare:

• Ich packe morgens ... = I pack ... in the mornings
• am Morgen = in the morning
• heute Morgen = this morning

So morgens often suggests a repeated habit, not just one specific morning.

German main clauses usually follow the verb-second rule. The conjugated verb must come in the second position.

In this sentence, Morgens takes the first position, so the verb packe must come second:

• Morgens | packe | ich ...

If you start with the subject instead, that is also correct:

• Ich packe morgens in die Wickeltasche ...

Both are grammatical. The original sentence puts a little more emphasis on Morgens.

Because in is a two-way preposition in German. It can take either:

• accusative for movement/direction
• dative for location

Here the idea is putting things into the bag, so there is movement toward the inside of the bag. That is why German uses the accusative:

• in die Wickeltasche = into the diaper bag

Compare:

• Ich packe die Sachen in die Wickeltasche. = I put the things into the diaper bag.
• Die Sachen sind in der Wickeltasche. = The things are in the diaper bag.

Wickeltasche means diaper bag or changing bag.

It is made up of:

• wickeln = to wrap / to change a baby
• die Tasche = bag

So it is literally a bag used for baby-changing items.

It is a feminine noun:

• die Wickeltasche
• accusative singular: also die Wickeltasche

This is a very common German structure meaning:

• not only ..., but also ...

In the sentence:

• nicht nur ein Fläschchen, sondern auch zwei Windeln und eine Decke

= not only a baby bottle, but also two diapers and a blanket

German uses this pair much like English uses not only ... but also ....

A few more examples:

• Er ist nicht nur nett, sondern auch lustig.
  = He is not only nice, but also funny.

• Sie spricht nicht nur Deutsch, sondern auch Englisch.
  = She speaks not only German, but also English.

Because nicht nur usually goes directly before the thing it is focusing on.

Here the first focused item is:

• ein Fläschchen

So German places nicht nur right before it:

• ... nicht nur ein Fläschchen, sondern auch ...

That tells you the contrast is between the packed items:

• not only a baby bottle
• but also two diapers and a blanket

If nicht nur were placed somewhere else, the focus could shift.

Fläschchen is a diminutive form of Flasche.

The ending -chen often means something like small or little, but sometimes it becomes the normal word for a specific object. In this context, Fläschchen often means baby bottle.

Important grammar point:

• nouns ending in -chen are always neuter

So:

• das Fläschchen
• ein Fläschchen

That is also why you do not get einen here. Only masculine nouns change to einen in the accusative singular.

Compare:

• der Ball → einen Ball
• das Fläschchen → ein Fläschchen

Because zwei Windeln is plural, while eine Decke is singular.

• die Windel = diaper
• plural: die Windeln

After a number like zwei, German normally uses the plural noun without an article:

• zwei Windeln = two diapers

And:

• die Decke = blanket
• eine Decke = a blanket

All of these are objects of packe, so they are in the accusative, but for these nouns the forms happen to look like this:

• ein Fläschchen — neuter singular accusative
• zwei Windeln — plural
• eine Decke — feminine singular accusative

Because in standard German, sondern is preceded by a comma.

So the pattern is:

• nicht nur ..., sondern auch ...

You should learn this as a fixed punctuation pattern.

Example:

• Er hat nicht nur Kaffee, sondern auch Tee gekauft.

Yes, absolutely.

Both are correct:

• Morgens packe ich in die Wickeltasche ...
• Ich packe morgens in die Wickeltasche ...

The difference is mainly one of emphasis and sentence flow:

• Morgens packe ich ... puts mornings first, so it feels a bit more topical or emphasized.
• Ich packe morgens ... starts more neutrally with the subject.

German is more flexible than English about what can come first in a sentence, as long as the conjugated verb stays in second position.

Yes, it could.

For example:

• Morgens packe ich nicht nur ein Fläschchen, sondern auch zwei Windeln und eine Decke in die Wickeltasche.

That is grammatical too.

The original version puts in die Wickeltasche earlier, which helps set the scene first: we learn right away where the things are being packed. German often allows this kind of flexibility in word order.

So both versions work, but the original sounds very natural.

Mostly yes, but in sentences like this it can also feel closer to put or pack into.

So:

• etwas in die Tasche packen

can mean:

• to pack something into the bag
• to put something into the bag

German packen is often used for placing items into a container, bag, suitcase, and so on. So the wording is very natural here.