Mater puerum monet ut lente per viam ambulet, quia glacies adhuc manet.

Because monet takes a direct object: the person being warned, advised, or reminded.

• mater = the mother
• puerum = the boy

So mater puerum monet means the mother warns/advises the boy.

This is a very common pattern with moneo, monere:
someone warns/advises someone.

After verbs like moneo in the sense of advise, warn, or urge, Latin often uses:

• moneo + accusative person + ut + subjunctive

So:

• mater puerum monet
• ut lente per viam ambulet

together mean: the mother advises/warns the boy to walk slowly along the road.

In English, we often use an infinitive: warns the boy to walk slowly.
Latin usually prefers ut + subjunctive here instead of a simple infinitive.

Because it is in an ut clause depending on monet.

This kind of ut clause expresses what someone is being urged, advised, or warned to do. In Latin, that requires the subjunctive.

So:

• ambulet = that he may walk / that he should walk
• in smoother English: to walk

It is not subjunctive because the action is doubtful; it is subjunctive because the grammar of the construction requires it.

Because lente is an adverb, and it describes how the boy should walk.

• lentus, lenta, lentum = slow as an adjective
• lente = slowly as an adverb

Since it modifies ambulet (walk), Latin uses the adverb:

• lente ambulet = he should walk slowly

Per takes the accusative, so viam is accusative singular of via.

Together, per viam literally means through the road or along the road, but in natural English here it is best understood as:

• along the road
• or simply on the road

So lente per viam ambulet means that he should walk slowly along the road.

Because the preposition per always takes the accusative case.

So:

• via = nominative
• viam = accusative

This is not because viam is the direct object of ambulet. It is accusative because it is the object of the preposition per.

It is a causal clause introduced by quia, meaning because.

So the sentence gives the reason for the mother's warning:

• quia = because
• glacies adhuc manet = ice still remains

This explains why the boy should walk slowly.

Because quia here introduces a straightforward statement of fact:

• glacies adhuc manet = the ice still remains

Latin normally uses the indicative after quia when the cause is presented as a real fact.
So manet is just an ordinary present indicative.

Adhuc means still, up to this point, or yet.

So:

• glacies manet = the ice remains
• glacies adhuc manet = the ice still remains

It emphasizes that the icy condition has not gone away yet.

Because glacies is a noun of the fifth declension, and its nominative singular is glacies.

Here it is the subject of manet:

• glacies = ice
• manet = remains

So glacies is nominative singular, not plural.

This can be confusing because English speakers may associate -es endings with plurals, but in Latin that is not always true.

In this sentence, warn or advise is better than remind.

The verb moneo can mean several related things depending on context:

• remind
• warn
• advise

Because the mother is telling the boy how to behave due to danger from ice, warns or advises fits best.

Latin word order is more flexible because grammatical relationships are shown largely by case endings rather than by position.

So in:

• Mater puerum monet ut lente per viam ambulet, quia glacies adhuc manet

you can tell:

• mater is the subject
• puerum is the object
• ambulet belongs in the ut clause
• glacies is the subject of manet

The sentence is not random, though. The order feels natural because Latin often places:

• the main verb fairly early or mid-sentence,
• the subordinate verb later,
• and the reason clause after the main idea.

Normally, with moneo meaning advise/warn, classical Latin prefers ut + subjunctive rather than a simple infinitive for the action advised.

So:

• mater puerum monet ut lente per viam ambulet

is the standard kind of construction.

English says warns the boy to walk slowly, but Latin usually does not copy that structure directly here.

Yes. Ambulet is present subjunctive, which is the normal tense in a primary sequence after monet (present tense).

• monet = present
• ambulet = present subjunctive

This shows action that is contemporaneous with or subsequent to the warning: the mother is warning him now about how he should walk.

If the main verb were past, Latin might use the imperfect subjunctive instead.

It breaks down like this:

• Mater puerum monet = main clause
• ut lente per viam ambulet = clause of advising/warning
• quia glacies adhuc manet = reason clause

So the grammar is:

subject + object + main verb + ut-clause + quia-clause

That is a very useful pattern to recognize in Latin.