One of the more confusing concepts for me as an English-speaker learning Spanish is that English has a clear difference between "to close" and "to lock"
The default words in Spanish abrir "to open" and cerrar "to close" also carry double meanings as "to unlock" and "to lock" respectively
In context that can make sense because if you're saying la tienda estĂĄ cerrada it means "the store is closed" but could also mean "the store is locked"
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The default way to explicitly say "to lock (something; usually doors)" is to say cerrar con llave which means "to close with a key", and una puerta cerrada con llave means "a locked door" rather than simply a "closed door"
There exists a scenario where the door is closed but not locked, and that's when con llave can help
Another thing that I've seen is people will say con seguro or sin seguro which threw me off for a minute
See - el seguro is in my head "insurance" as in health insurance of car insurance; when it isn't seguro/a the adjective meaning "sure" or "certain"
But el seguro is another word for a "lock" or "deadbolt" [others include la cerradura or el cerrojo; and el cierre as well, though el cierre can also mean "fastener" for clothes like a button hole or a zipper]
So if you're trying to tell someone "the door's open" you can say la puerta estĂĄ abierta "the door is open/unlocked" but if you specifically want to say "the door's open" as in someone is knocking and you're telling them the door's lock isn't in place you can say la puerta estĂĄ sin seguro "the door's lock hasn't been put in place" like saying "I didn't use the deadbolt"
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Two slightly unrelated notes; if you're telling someone to "come in" as in giving them access, you can often say adelante which is literally "forward" - or you can use a command form of pasar "to pass"; saying pasa or pase [the usted command] when someone knocks is very common
The other unrelated note is that el cerrojo and la cerradura seem to be interchangeable; they're both related to cerrar ... and el cierre is often "the locking mechanism" on something
Two additional words you might need - la bocallave is "keyhole", literally "mouth-key", and el candado "padlock"
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A final and very tangential note - la llave has more uses than just "key"
It can refer to a "faucet" or "spigot" for water
It can mean "wrench", which la llave inglesa having thrown me off because that is the basic wrench you're thinking of but it's literally "English key"
And in wrestling, la llave is another word for a "hold" or a "lock", like headlocks or leglocks
I only mention it because there have been quite a few times where I could not figure out why llave was being used until I remembered it has so many secondary meanings
There were two other things I thought to add:
First - in general you can also see bloqueado/a or desbloqueado/a used for "locked/unlocked" particularly in gaming or with memories; it literally means "blocked" or "unblocked"
But in gaming you might see mejora desbloqueada "upgrade unlocked" [lit. "improvement unlocked"] and also for achievements
Memories can also be bloqueado/a or desbloqueado/a
If you use it with doors/windows it tends to mean "something is blocking it" like it's in the way - not necessarily that it's locked, but it could be
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And the second thing is the expression a cal y canto which is sometimes seen as a calicanto
This means "bricked up" usually, but can mean "shut up tight" or "blocked off"
The expression is originally a cal y canto which means "by/with lime(stone) and stone"
la cal is "lime" or "whitewash", while el canto is another word for "stone" - less common in general, but still used in some contexts [and la cantera is "quarry"; but it would mean "the place of stone / where stone is kept" etc.]
In other words this is the expression for "brick and mortar"
In every day context el ladrillo is a "brick", but a cal y canto is like Cask of Amontillado, making a brick wall and completely sealing something off - and it got shortened as a calicanto
You see this expression to mean "locked up tight" or "completely sealed off", but it would have originally been what you do to brick off a room or a fireplace
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If you see cerrar a calicanto it is like sellar "to seal" just the expression indicates no possible way in
