Im Gefrierfach liegen noch Beeren für den Joghurt und eine Packung Eis für das Wochenende.

Im is the contraction of in dem.

So:

• in dem Gefrierfach → im Gefrierfach

It uses the dative case because this sentence describes location: where something is.

• im Gefrierfach = in the freezer compartment

A useful contrast:

• im Gefrierfach = in the freezer compartment (already there, location)
• ins Gefrierfach = into the freezer compartment (movement/direction)

So here, because the berries and ice cream are already there, im is correct.

German often puts the location first if that is the setting or the thing being emphasized.

The normal word order rule for a main clause is:

• Position 1: one element
• Position 2: the finite verb

Here:

• Im Gefrierfach = position 1
• liegen = position 2

After that comes the rest:

• noch Beeren für den Joghurt und eine Packung Eis für das Wochenende

So the sentence structure is perfectly normal German. English usually keeps the subject first more often, but German is more flexible.

German often uses a position verb where English would simply use to be.

Here, liegen means to lie or to be lying. For objects, it often just means to be located somewhere, especially when they are stored or resting there.

So:

• Im Gefrierfach liegen Beeren. = There are berries in the freezer compartment / Berries are in the freezer compartment.

German commonly uses:

• liegen for things lying flat or simply being there
• stehen for things standing upright
• hängen for things hanging

In everyday German, this sounds more natural than using sein in many situations.

Because the subject is effectively plural.

The things in the freezer are:

• Beeren
• eine Packung Eis

Together, that makes a compound subject:

• Beeren ... und eine Packung Eis

That takes a plural verb, so:

• liegen = plural
• liegt = singular

Even though eine Packung is singular by itself, the whole subject is made of two items joined by und, so the verb is plural.

Here noch means something like:

• still
• still some
• still left
• remaining

So the sentence suggests that these things are still available in the freezer.

For example:

• Im Gefrierfach liegen noch Beeren ... = There are still berries in the freezer ... = There are berries left in the freezer ...

That small word adds the idea that the items have not been used up yet.

Because German often uses a bare plural when it means some berries or berries in general.

So:

• Beeren here means something like berries or some berries

If you said die Beeren, that would sound more specific:

• die Beeren = the berries (specific berries already known from the context)

In this sentence, the speaker is just listing what is there, so Beeren without an article is very natural.

It means the berries are intended for the yogurt or to go with the yogurt.

So the idea is:

• the berries are there for eating with yogurt

Also, für always takes the accusative case, which is why it is:

• für den Joghurt

because Joghurt is usually masculine:

• der Joghurt
• accusative: den Joghurt

In natural English, you might translate this more loosely as:

• for the yogurt
• for yogurt
• to have with yogurt

Here Eis means ice cream.

In food contexts, Eis very often means ice cream in German. So:

• eine Packung Eis = a pack/tub/carton of ice cream

It does not mean a package of frozen water here.

The context makes that clear:

• it is in the freezer
• it is for the weekend
• Packung sounds like packaged food

So this is naturally understood as ice cream.

It means the ice cream is for the weekend, in the sense of:

• intended for the weekend
• saved for the weekend
• to be eaten on the weekend

Again, für takes the accusative, so:

• das Wochenende is correct because Wochenende is neuter:
  • das Wochenende

So:

• eine Packung Eis für das Wochenende = a pack of ice cream for the weekend

Gefrierfach means freezer compartment or freezer section.

It is not the same as:

• der Kühlschrank = the refrigerator
• der Gefrierschrank = the freezer as a separate appliance

A Gefrierfach is often:

• the freezer section inside a fridge
• a freezer drawer/compartment

So im Gefrierfach means the food is in that frozen-storage part, not just in the fridge in general.