Το κορδόνι μου λύνεται συνέχεια όταν περπατάω γρήγορα.

Κορδόνι literally means lace, cord, string, or shoelace, depending on context.

In this sentence, it most naturally means shoelace, because of the idea of it coming undone while walking. Greek often uses one everyday word where English may choose a more specific one from context.

In normal Greek, possessed nouns usually still take the definite article.

So:

• το κορδόνι μου = my lace / my shoelace
• η τσάντα μου = my bag
• το σπίτι μου = my house

To an English speaker, το κορδόνι μου may look like the shoelace my, but that is just standard Greek structure.

Μου means my here.

More precisely, it is the weak genitive form of the pronoun εγώ. Greek often uses these weak pronoun forms after the noun to show possession:

• το βιβλίο μου = my book
• ο φίλος μου = my friend
• το κορδόνι μου = my shoelace

So μου is not optional here if you want to say whose shoelace it is.

Λύνεται is the mediopassive form of the verb λύνω.

• λύνω = I untie / I loosen
• λύνεται = it comes undone / it gets untied / it is being untied

In this sentence, the shoelace is not actively untieing something else. Instead, something is happening to it, so Greek uses the mediopassive form.

Here it means comes undone.

That is an important point. The Greek mediopassive can sometimes sound more natural in English as an intransitive idea rather than a true passive.

So:

• Το κορδόνι μου λύνεται = My shoelace comes undone
• not necessarily My shoelace is being untied by someone

Context tells you which meaning is intended, and here comes undone is the natural one.

Greek does not need a separate verb for keeps here. The idea is expressed by:

• the present tense λύνεται
• plus συνέχεια

So λύνεται συνέχεια means something like:

• keeps coming undone
• comes undone all the time
• is constantly coming undone

This is a very common Greek way to express repeated or annoying repetition.

Here συνέχεια means constantly, continually, or all the time.

By itself, συνέχεια is also a noun meaning continuation or continuity in other contexts. But in everyday speech it is very often used adverbially to mean non-stop / repeatedly.

So in this sentence:

• λύνεται συνέχεια = keeps coming undone / comes undone all the time

A similar word is συνεχώς, which also means continuously / constantly.

It can mean either, depending on context.

In this sentence, because the whole idea is habitual and repeated, όταν is best understood as when(ever) or whenever:

• όταν περπατάω γρήγορα = when / whenever I walk fast

English often prefers whenever to make the repeated meaning clearer, but plain when can also work.

Because the sentence describes a habitual or repeated situation, not a one-time event.

So Greek uses the present tense in both parts:

• λύνεται = comes undone / keeps coming undone
• περπατάω = I walk

Together they describe something that regularly happens: My shoelace keeps coming undone when I walk fast.

Yes. Both mean I walk.

• περπατάω is very common in everyday speech
• περπατώ is also correct and may sound a bit more compact or slightly more formal

So these are both normal:

• όταν περπατάω γρήγορα
• όταν περπατώ γρήγορα

A learner should recognize both.

Because γρήγορα is being used as an adverb, meaning quickly / fast, and it modifies the verb περπατάω.

So:

• γρήγορος = fast, quick as an adjective for a noun
• γρήγορα = quickly, fast as an adverb

Here it answers How do I walk? → γρήγορα

Not completely. Greek word order is more flexible than English, although the original sentence is very natural.

Original:

• Το κορδόνι μου λύνεται συνέχεια όταν περπατάω γρήγορα.

You could also hear variations such as:

• Το κορδόνι μου όταν περπατάω γρήγορα λύνεται συνέχεια.
• Συνέχεια λύνεται το κορδόνι μου όταν περπατάω γρήγορα.

These versions may shift emphasis, but the basic meaning stays the same. The original order is probably the most neutral and natural for a learner to use.

Yes, Greek could use either singular or plural depending on the situation.

• Το κορδόνι μου = my shoelace / one of my shoelaces
• Τα κορδόνια μου = my shoelaces

The singular is perfectly normal if one lace is the problem, or if the speaker is thinking of a single lace in particular. If both laces keep coming undone, Greek could say:

• Τα κορδόνια μου λύνονται συνέχεια όταν περπατάω γρήγορα.