Questions & Answers about दरवाज़े पर ताला है।
Because Hindi nouns usually change to the oblique form before a postposition such as पर.
- Direct form: दरवाज़ा = door
- Oblique form: दरवाज़े
- So: दरवाज़े पर = on/at the door
This is a very common pattern with masculine nouns ending in -ा.
पर is a postposition meaning on, at, or upon, depending on context.
In दरवाज़े पर ताला है, it shows location: the lock is on the door / at the door. English may translate this in slightly different ways, but the basic idea is location.
Hindi often puts the location first and then the thing that exists there.
So this sentence is literally close to:
On the door, a lock is.
That is a normal Hindi way to express There is a lock on the door.
You could also say ताला दरवाज़े पर है, but that puts a bit more focus on the lock itself.