Je lis en silence dans le jardin.

Because lis is the je form of the verb lire (to read) in the present tense, and in French many verb endings are written but not pronounced.

• je lis → pronounced lee
• tu lis → also lee
• il/elle lit → also lee

So lis and lit sound the same, even though they are spelled differently.

It is the present tense: I read or I am reading.

French present tense often covers both meanings that English separates:

• Je lis = I read
• Je lis = I am reading

The exact meaning depends on context.

French often uses a preposition + noun where English uses an adverb.

So:

• en silence = in silence / silently

This is a very natural French expression. French does also have silencieusement, but en silence is more common and usually sounds more everyday and idiomatic here.

Because en silence is a fixed expression.

French has many common expressions with en + noun and no article, especially when they describe manner or state:

• en silence = silently
• en colère = angry
• en secret = secretly
• en public = in public

So en silence is just the normal form.

Dans means in or inside/within, so dans le jardin means in the garden.

This is the most straightforward choice here. It places the action physically in that space.

• dans le jardin = in the garden

You may sometimes see au jardin in certain contexts, but dans le jardin is the standard, neutral way to say it here.

Le jardin means the garden, while un jardin means a garden.

French uses le/la/les when the speaker assumes the listener can identify the thing, or when the context makes it feel like a specific place.

So:

• dans le jardin = in the garden
• dans un jardin = in a garden

Both are grammatically correct, but they mean slightly different things.

Yes. That is also correct.

Both are natural:

• Je lis en silence dans le jardin.
• Je lis dans le jardin en silence.

The difference is mostly about focus or rhythm:

• en silence first: highlights how
• dans le jardin first: highlights where

French has some flexibility with adverbial phrases like these.

It mainly describes how the reading happens, so it modifies the action of reading.

In other words:

• Je lis → the action
• en silence → the manner: silently
• dans le jardin → the place: in the garden

So the sentence breaks down like this:

• Je = subject
• lis = verb
• en silence = manner
• dans le jardin = location

A natural pronunciation is roughly:

zhuh lee ahn see-lahns dahn luh zhar-dan

A more accurate breakdown:

• Je → like zhuh
• lis → lee
• en → nasal vowel, not on
• silence → see-lahns
• dans → nasal vowel
• le → luh
• jardin → zhar-dan with a French r

Important points:

• The s in lis is silent.
• The n in en, dans, and the end of jardin helps create a nasal sound; it is not pronounced like a full English n.
• j in jardin sounds like the s in measure.

Not really in the usual careful pronunciation.

For example:

• Je lis en silence does not normally create a pronounced liaison with the s of lis
• dans le jardin also does not involve a special liaison here

A learner can safely pronounce each word normally without trying to add extra linking sounds.

It comes from lire (to read), which is somewhat irregular.

Present tense:

• je lis
• tu lis
• il/elle/on lit
• nous lisons
• vous lisez
• ils/elles lisent

Things learners often notice:

• je lis / tu lis / il lit all sound very similar
• nous lisons and vous lisez clearly show the stem with extra pronounced endings

So yes, lire is not a completely regular -re verb.

Not usually. Lire specifically means to read.

If you want I study, you would normally say:

• J’étudie = I study
• Je travaille = I work / I study

So in this sentence, je lis clearly means I am reading or I read.

There are several common ways:

• Tu lis en silence dans le jardin ?
  Casual spoken French: Are you reading silently in the garden?

• Est-ce que tu lis en silence dans le jardin ?
  Very common and neutral.

• Lis-tu en silence dans le jardin ?
  More formal or written style.

If you want to keep I instead of you, you would normally ask something like:

• Est-ce que je lis en silence dans le jardin ? = Am I reading silently in the garden?

But that is less common in everyday use unless you are checking or clarifying something.