Il telo protegge il rivestimento.

Because both nouns are singular masculine nouns.

• il telo = the tarp / the sheet / the cloth
• il rivestimento = the covering / the lining / the coating / the upholstery

In Italian, the definite article must agree with the noun in gender and number.
Here:

• telo is masculine singular → il
• rivestimento is masculine singular → il

So il is used twice because there are two separate masculine singular nouns.

A common clue is the ending:

• telo ends in -o, which is very often masculine singular
• rivestimento also ends in -o, so it is also masculine singular

This is not a perfect rule for every noun in Italian, but it is a very useful pattern.

Their plurals are:

• il telo → i teli
• il rivestimento → i rivestimenti

That plural pattern also confirms they are masculine nouns.

Protegge is the third-person singular present tense of proteggere (to protect).

So it can mean:

• he protects
• she protects
• it protects

In this sentence, the subject is il telo, so the natural English translation is the tarp/sheet protects the covering.

A quick conjugation in the present tense:

• io proteggo = I protect
• tu proteggi = you protect
• lui/lei protegge = he/she/it protects
• noi proteggiamo = we protect
• voi proteggete = you all protect
• loro proteggono = they protect

Because Italian usually does not need subject pronouns when the subject is already clear.

Instead of saying something like It protects the covering, Italian simply says:

• Il telo protegge il rivestimento.

The noun il telo already tells you what is doing the action, so adding a pronoun like esso would normally sound unnecessary or unnatural in everyday Italian.

Italian often works this way:

• Mangio = I eat
• Parliamo = we speak
• Il telo protegge il rivestimento = The tarp protects the covering

This is the normal Italian order:

subject + verb + object

• Il telo = subject
• protegge = verb
• il rivestimento = direct object

So literally the structure is:

• The tarp protects the covering

Italian can sometimes change word order for emphasis, but this sentence is in the most neutral and standard order.

Because the infinitive is proteggere, and this verb keeps the gg in forms like protegge.

This is just part of the verb’s spelling pattern. Compare:

• proteggere = to protect
• proteggo = I protect
• proteggi = you protect
• protegge = he/she/it protects

The double g is important in both spelling and pronunciation.

Protegge is pronounced roughly like:

pro-TEJ-je

More exactly, the gg before e makes a sound like the dg in bridge or the j in jam.

A rough guide:

• pro- as in pro
• -teg- / -tegg- with a soft j sound
• final -e pronounced clearly, not silent

So it is not pronounced like English protect. The ending matters, and the final e is sounded.

Yes. Il rivestimento is the direct object of protegge.

To find the direct object, ask: What does the tarp protect?

Answer: the covering / the lining / the upholstery

So:

• Il telo = the thing doing the action
• protegge = the action
• il rivestimento = the thing receiving the action

Not in normal Italian.

Italian uses articles much more often than English does. In a sentence like this, leaving them out would sound wrong or very unnatural.

So you normally say:

• Il telo protegge il rivestimento.

not

• Telo protegge rivestimento.

In Italian, articles are usually required with countable nouns like these unless there is a special reason to omit them.

Yes, especially because telo and rivestimento can both be translated in different ways depending on the situation.

For example:

• telo can mean sheet, cloth, canvas, cover, or tarp
• rivestimento can mean covering, lining, coating, upholstery, or surface layer

So the grammar stays the same, but the exact English wording may change depending on context.

For example, in different settings it could refer to:

• a protective sheet over furniture
• a cover protecting upholstery
• a fabric layer protecting a lining
• a sheet protecting a surface coating

A few common possibilities are:

• I teli proteggono il rivestimento.
  The sheets/tarps protect the covering.

• Il telo protegge i rivestimenti.
  The sheet/tarp protects the coverings.

• I teli proteggono i rivestimenti.
  The sheets/tarps protect the coverings.

Notice the changes:

• il → i for masculine plural
• telo → teli
• rivestimento → rivestimenti
• protegge → proteggono when the subject becomes plural

Not exactly.

• Il telo protegge il rivestimento = The tarp/sheet protects the covering
  This is a simple present statement. It can describe a general fact or current function.

• Il telo sta proteggendo il rivestimento = The tarp/sheet is protecting the covering
  This emphasizes an action happening right now.

Italian often uses the simple present where English might use either the simple present or present continuous, so protegge is very common and natural.