Ne metu pneŭon sur la radon ĝis la flikaĵo estos preta.

Metu is the -u form, which is used for commands, requests, instructions, and similar ideas.

So:

• meti = to put
• metas = puts / is putting
• metu = put! / let ... put / should put

Because this sentence is giving an instruction, Esperanto uses metu. With ne, it becomes a negative command:

• Ne metu = Don’t put

The -n marks the direct object.

Here, the thing being put is the tire, so pneŭon is the object of metu:

• meti ion = to put something
• here, that something is pneŭon

So pneŭon means a tire or the tire, depending on context.

Because sur can show either:

• location: sur la rado = on the wheel
• direction/movement onto something: sur la radon = onto the wheel

In this sentence, the action is putting the tire onto the wheel, so Esperanto uses -n to show movement toward a place.

This is a very common pattern:

• sur la tablo = on the table
• sur la tablon = onto the table

So sur la radon is correct because the tire is being moved onto the wheel.

Esperanto has the definite article la, but it has no indefinite article like English a/an.

So:

• pneŭon can mean a tire
• la radon = the wheel
• la flikaĵo = the patch

Why no la before pneŭon? Because the sentence does not present the tire as a specifically identified one, at least not grammatically. It is simply a tire / tire in general.

By contrast, la radon and la flikaĵo refer to specific things understood in the situation.

Ĝis means until or up to the point when.

It introduces the point at which the main action becomes allowed or changes. So:

• Ne metu pneŭon sur la radon ĝis...
  = Do not put a tire on the wheel until...

In other words, wait up to the moment when the patch is ready.

That is a very common question for English speakers.

Esperanto often uses the tense that matches the actual time of the event. Here, the patch becoming ready is in the future relative to the instruction, so estos is natural:

• la flikaĵo estos preta = the patch will be ready

English usually avoids will after until, but Esperanto does not follow that English rule in the same way.

So ĝis la flikaĵo estos preta is normal Esperanto.

Because preta is a predicate adjective after esti.

In la flikaĵo estos preta:

• la flikaĵo is the subject
• estos is the verb
• preta describes the subject

It is not a direct object, so it does not take -n.

Compare:

• La flikaĵo estas preta. = The patch is ready.
• Mi vidas la pretan flikaĵon. = I see the ready patch.

In the second example, pretan has -n because it belongs to the direct object flikaĵon. But after esti, you normally get plain preta.

It is built from parts:

• flik- = patch, mend
• -aĵ- = a concrete thing, item, or result
• -o = noun ending

So flikaĵo literally means something like a patch-item or a thing used for patching.

In normal English, that is just a patch.

This is a useful suffix to learn. For example, -aĵ- often creates the name of a thing or product related to the root.

Yes. Pretos is also possible.

Esperanto adjective roots can often be used directly as verbs:

• La flikaĵo estos preta.
• La flikaĵo pretos.

Both mean the patch will be ready.

The version with estos preta may feel a little more explicit to some learners, while pretos is shorter and very natural Esperanto.