Les billes d’argile couvrent le trou de drainage.

Les is the plural definite article in French, meaning the before a plural noun.

Here, billes is plural, so French uses les billes = the clay balls / the clay pebbles.

French articles are used more regularly than in English, so you usually cannot just leave them out.

Because the noun is referring to more than one ball or pellet.

The singular would be:

La bille d’argile couvre le trou de drainage.
= The clay ball covers the drainage hole.

In your sentence, billes ends in -s, and the verb also changes to match the plural subject.

Literally, bille often means ball, marble, or small round pellet/object, depending on context.

In gardening or potting contexts, billes d’argile usually refers to clay pebbles, expanded clay balls, or LECA-type pellets.

So even though bille can mean marble in other situations, here it refers to the round clay pieces used in planting.

In billes d’argile, the phrase de + noun is being used to describe the material or type: balls of clay / clay balls.

Before a vowel sound, de becomes d’, so:

de argile → d’argile

You do not use de l’argile here because this is not the partitive meaning some clay. It is a noun complement describing what the balls are made of.

Compare:

• des billes d’argile = clay balls
• de l’argile = some clay

Because the subject is plural: Les billes d’argile.

The verb couvrir must agree with its subject:

• je couvre
• tu couvres
• il/elle couvre
• nous couvrons
• vous couvrez
• ils/elles couvrent

So:

• La bille couvre... = singular
• Les billes couvrent... = plural

Even though couvrent is spelled differently from couvre, they are pronounced the same in standard French.

The subject is Les billes d’argile.

A good way to find it is to ask: What is doing the action?

What covers the drainage hole?
The clay balls do.

So:

• Subject: Les billes d’argile
• Verb: couvrent
• Object: le trou de drainage

Because trou is a masculine singular noun.

So the definite article is le:

• le trou = the hole

If the noun were feminine, you would use la.
If it were plural, you would use les.

De drainage is a noun complement that specifies the type of hole.

So un trou de drainage means a drainage hole.

This structure is very common in French:

• une table de cuisine = a kitchen table
• un verre de vin = a glass of wine
• un trou de drainage = a drainage hole

French often uses de + noun where English uses a noun directly as an adjective-like modifier.

Because French generally does not stack nouns together the way English does.

English easily says:

• drainage hole
• garden soil
• plant pot

French usually needs a linking structure, often de:

• trou de drainage
• terre de jardin
• pot de fleurs

So de is the normal way to connect the nouns here.

Yes. The sentence follows the standard French order:

Subject + Verb + Object

• Les billes d’argile = subject
• couvrent = verb
• le trou de drainage = object

This is the most neutral and common word order in French.

A careful pronunciation is approximately:

lay bee-y duh-zhar-zheel koovr luh troo duh dreh-nahzh

A few useful notes:

• Les sounds like lay
• billes sounds like bee-y
• d’argile links smoothly; the d’ is very short
• couvrent is pronounced roughly like koovr
• the -ent ending in couvrent is silent
• drainage in French sounds like dreh-nahzh, not like the English word

Yes, several.

Common silent letters here include:

• the final -s in les
• the final -s in billes
• the final -ent in couvrent
• often the final -e in drainage is not pronounced as a full sound

This is very common in French, so spelling and pronunciation often do not match as closely as in English.

Sometimes, yes, but the meaning changes slightly.

• couvrir = to cover
• recouvrir = to cover over, to coat, to cover completely

So couvrent is the simpler and more neutral choice.
Recouvrent might sound a bit stronger, as if the clay balls cover the hole more fully or form a layer over it.

Grammatically, it uses definite articles everywhere:

• Les billes
• le trou

That often suggests something specific in context: the clay balls and the drainage hole of a particular pot or setup.

However, French also uses definite articles more often than English, so depending on context it could still sound like a general instruction, especially in practical or instructional writing.

Yes. Argile means clay.

For example:

• L’argile est humide. = The clay is damp.
• C’est de l’argile. = It is clay / It’s some clay.

In your sentence, though, argile is part of the expression billes d’argile, which functions like a fixed gardening term.