Serva ampullam in armario deponit, ne infans eam tangat.

Because serva is in the nominative singular, the case normally used for the subject of a sentence.

• serva = the female servant / slave-girl
• It matches the verb deponit = puts down / places

So serva ... deponit means that the servant is the one doing the action.

Because ampullam is the direct object of deponit, so it is in the accusative singular.

• nominative: ampulla
• accusative: ampullam

Latin often marks the object by changing the ending, whereas English usually relies more on word order.

So ampullam deponit means she places the bottle/flask.

Because in can take either the accusative or the ablative, depending on the meaning.

Here it means in / inside in the sense of location, not motion toward a place. So Latin uses the ablative:

• in armario = in the cupboard / cabinet

Compare:

• in armario = in the cupboard (location, ablative)
• in armarium = into the cupboard (motion toward, accusative)

Since the bottle is being placed and ends up there as a location, in armario is the expected form.

Armario is the ablative singular of armarium, a neuter second-declension noun.

Its basic forms are:

• nominative singular: armarium
• genitive singular: armarii
• ablative singular: armario

So after in expressing location, armario is the correct case form.

Latin word order is much freer than English word order because the endings show grammatical roles. A verb often comes near the end of its clause, though that is not a strict rule.

So:

• Serva ampullam in armario deponit

is a very natural Latin order: subject – object – place – verb.

English needs a more fixed order, but Latin can move words around for emphasis or style without changing the basic meaning.

Here deponit means something like puts down, places, or sets in a place.

It is:

• 3rd person singular
• present tense
• active voice
• from deponere

So it means she puts / she is putting / she places.

In context, it suggests that the servant is placing the bottle in the cupboard.

Because ne introduces a negative purpose clause.

The idea is:

• she puts the bottle in the cupboard
• so that the child may not touch it

Latin uses:

• ut = so that
• ne = so that ... not

So ne infans eam tangat means so that the child does not / may not touch it.

This is different from English, where we usually just use so that ... not.

Because it is in a purpose clause introduced by ne.

In Latin, purpose clauses normally use:

• ut
  • subjunctive = so that
• ne
  • subjunctive = so that ... not

So tangat is the present subjunctive of tangere.

That subjunctive does not mean uncertainty here. It signals the kind of clause: a clause of purpose.

Because eam is the accusative singular feminine form of the pronoun is, ea, id.

It refers back to ampullam, which is:

• feminine
• singular
• the object of tangat

So:

• infans eam tangat = the child may touch it
• literally, the child may touch her/it

Since ampulla is feminine in Latin, the pronoun must also be feminine: eam.

Because it matches ampullam in gender and number:

• ampullam = feminine singular
• eam = feminine singular accusative

Also, it makes perfect sense in context: the servant puts the bottle away so that the child will not touch it, meaning the bottle.

Infans is in the nominative singular, because it is the subject of tangat.

Even though its form does not change between nominative and accusative in some contexts, here the role is clear from the sentence:

• infans = the child
• eam = it
• tangat = may touch

So infans is the one doing the touching.

Yes. Infans is grammatically a third-declension noun and can refer to a child without specifying sex.

So in context it may mean:

• the child
• the baby
• the infant

If the natural gender matters, Latin can make that clear elsewhere, but infans by itself is often general.

Because Latin expresses that idea differently from English.

English says:

• so that the child may not touch it

Latin uses a purpose construction:

• ne infans eam tangat

The word ne already carries the force of so that ... not, so no separate word for that is needed.

Yes. The Latin present tense often covers both of these English possibilities:

• she places
• she is placing

Which one sounds better depends on context. Latin does not always make the same aspect distinction that English does between simple present and present progressive.

So deponit can naturally be understood either way.

Yes. ne infans eam tangat depends on the main clause and explains why the servant puts the bottle in the cupboard.

Structure:

• main clause: Serva ampullam in armario deponit
• subordinate purpose clause: ne infans eam tangat

So the sentence means that the action of putting away the bottle is done for a purpose: to prevent the child from touching it.