Sub salice aestate libenter sedetur, quia umbra ibi densa est.

Because sub here means under in the sense of location, not motion.

Latin often uses:

• sub + ablative = under / beneath (where something is)
• sub + accusative = to under / up under (movement toward a place)

So:

• sub salice = under the willow
• if there were movement, Latin might use sub salicem

Here the idea is resting or sitting in a place, so the ablative salice is expected.

Salice comes from salix, salicis (feminine), meaning willow.

Its forms include:

• nominative singular: salix
• genitive singular: salicis
• ablative singular: salice

So sub salice literally means under a willow or under the willow, depending on context. Latin has no word for the, so the article is supplied by the translator.

Because Latin often uses the ablative of time when without a preposition.

So aestate means:

• in summer
• during the summer

This is a very common Latin pattern for time expressions. For example:

• hieme = in winter
• nocte = at night
• tertia hora = at the third hour

Latin can sometimes use in with seasons or times, but here the simple ablative aestate is perfectly normal.

Libenter is an adverb meaning:

• gladly
• willingly
• with pleasure

It modifies sedetur, so the idea is that sitting there is done pleasantly or willingly: people gladly sit there / one likes to sit there.

It comes from the adjective libens, libentis, meaning willing or pleased.

Sedetur is an impersonal passive form.

The verb sedeo, sedere means to sit. Since to sit is intransitive, it normally does not take a direct object. In Latin, the passive of an intransitive verb can be used impersonally in the 3rd person singular.

So sedetur means something like:

• there is sitting
• people sit
• one sits

In smoother English, we usually translate it with an indefinite subject:

• people gladly sit
• one gladly sits
• it is pleasant to sit

This is a very Latin way of expressing a general action without naming a specific subject.

Because English usually does not have a natural equivalent for this kind of impersonal passive.

Latin says sedetur, literally something like it is sat, but English it is sat does not normally mean people sit. So we translate according to the sense, not word-for-word.

That is why a natural English translation uses:

• people sit
• one sits
• it is pleasant to sit

So although sedetur is grammatically passive in Latin, its meaning in English is often best expressed by an indefinite active.

Because sedetur is impersonal.

With an impersonal verb, Latin does not need to name a person or thing doing the action. The action is presented generally:

• sedetur = people sit / one sits
• curritur = people run / one runs
• pugnatur = there is fighting / people fight

So the sentence is not about a particular person sitting under the willow; it is a general statement.

Quia means because and introduces a clause giving the reason:

• quia umbra ibi densa est = because the shade there is dense

So the structure is:

• main statement: Sub salice aestate libenter sedetur
• reason clause: quia umbra ibi densa est

This is straightforward Latin subordination, much like English because.

Because umbra is the subject of est in the clause umbra ibi densa est.

The clause means literally:

• the shade there is dense

So:

• umbra = subject, nominative singular
• densa = predicate adjective agreeing with umbra
• est = is

This is a standard subject + predicate adjective + est construction.

Because densa must agree with umbra.

Umbra is:

• feminine
• singular
• nominative

So the adjective must also be:

• feminine
• singular
• nominative

Hence densa.

This agreement is one of the most important features of Latin adjectives.

Ibi is an adverb meaning there.

It points back to the place already mentioned: under the willow.

So:

• umbra ibi densa est = the shade there is dense

Latin often uses adverbs like ibi to reinforce location. It helps connect the reason clause to the first part of the sentence.

It is flexible rather than unusual. Latin word order is much freer than English word order because the endings show the grammatical relationships.

The sentence is:

Sub salice aestate libenter sedetur, quia umbra ibi densa est.

A more English-like arrangement might be:

• Libenter aestate sub salice sedetur, quia ibi umbra densa est.

But the original order is perfectly natural. It puts the setting first:

• Sub salice = where?
• aestate = when?
• libenter sedetur = what happens?
• quia... = why?

So the word order helps the sentence unfold in a clear, descriptive way.

It can mean either, depending on context.

Latin has no definite or indefinite article, so salice by itself can be translated as:

• under a willow
• under the willow

The translator chooses whichever sounds best in context. If a specific willow has already been mentioned, the willow may be better. If the sentence is just a general description, a willow may fit better.

Yes. While densus, -a, -um literally means dense, thick, or close-packed, in context umbra densa can naturally suggest:

• thick shade
• deep shade
• heavy shade

So an idiomatic English translation may be less literal than dense shade. The important idea is that the willow provides a lot of shade, which explains why sitting there in summer is pleasant.