Cum imber desiit, puellae iterum foras exeunt et in horto ludunt.

Here cum means when. In context, it introduces a time clause: when the rain stopped.

You may also see cum mean since or although, but not here. The sense is clearly temporal.

Also, notice that cum is followed by the indicative here, not the subjunctive. That is normal for a straightforward time clause referring to a real event.

Imber is nominative singular, and it is the subject of desiit.

So:

• imber = rain / rainstorm / shower
• desiit = stopped

Together: the rain stopped.

Desiit is the 3rd person singular perfect active indicative of desinere, meaning to stop or to cease.

So imber desiit means:

• literally: the rain has stopped
• in normal past-time narration: the rain stopped

The perfect tense shows that the stopping is a completed action.

Yes, puellae is an ambiguous form by itself. It can be:

• nominative plural = girls
• genitive singular = of the girl
• dative singular = to/for the girl
• vocative plural = girls!

Here it must be nominative plural, because it is the subject of the plural verbs exeunt and ludunt.

So:

• puellae exeunt = the girls go out
• not to the girl goes out, which would not make grammatical sense

Iterum means again.

It is an adverb, so it modifies the action rather than a noun. Here it tells us that the girls go outside again.

Latin word order is flexible, so iterum could appear in different places without changing the basic meaning. In this sentence, its position is perfectly natural.

Foras is an adverb, not a noun and not a preposition.

It means outside, especially with the idea of motion toward the outside. So:

• foras exeunt = they go outside / they go out

This is different from a location expression such as outside in the sense of being outside.

Because Latin often combines a verb of motion with an adverb that reinforces or clarifies the direction.

So exeunt already suggests go out, but foras adds emphasis and makes the direction very explicit:

• exeunt = they go out
• foras exeunt = they go out outside / they go out of doors, more vividly

English does something similar:

• go out
• go outside

Both are present active indicative, 3rd person plural:

• exeunt = they go out
• ludunt = they play

In a story, Latin often uses the historical present: present-tense forms used to describe past events more vividly. So even though the forms are present, English may translate them as past if the context is narrative:

• the girls go out and play
• or, in smoother story English, the girls went out and played

So the present forms are not a mistake; they are a common storytelling feature.

Because in takes different cases depending on whether it shows location or motion.

Here it means in the garden, meaning where the girls are playing, so Latin uses the ablative:

• in horto = in the garden

If the sentence meant motion into the garden, Latin would use the accusative:

• in hortum = into the garden

So:

• in horto ludunt = they play in the garden
• not they play into the garden

Because Latin does not have articles like English the and a/an.

So a word like puellae can mean:

• girls
• the girls
• sometimes even some girls

The context tells you which English article makes best sense. In this sentence, English naturally uses the girls.

The same applies to imber and horto:

• imber = rain / the rain
• in horto = in a garden / in the garden

The word order is meaningful, but not as rigid as in English.

Latin often puts a subordinate clause first to set the scene:

• Cum imber desiit = When the rain stopped

Then the main action follows:

• puellae iterum foras exeunt et in horto ludunt

This order feels natural because it gives the background first and then tells what happened next.

Latin could rearrange parts of the sentence for emphasis, but the endings on the words would still show the grammar.

Et simply means and. It links the two actions done by the same subject:

• exeunt = they go out
• ludunt = they play

So:

• puellae iterum foras exeunt et in horto ludunt
• the girls go outside again and play in the garden

It joins two coordinated verbs with the same subject, which is very common in Latin.