A cafe is on the corner.
In English we like to put new information at the end of the sentence where it has emphasis. We like to put old information at the beginning of the sentence. Because we have already talked about these things they are easier to process. If we don't have any old information in a sentence, we like to put information that helps the listener to understand the situation, at the beginning. This is usually information about times or places. So at the beginning of a new piece of writing you are very likely to see sentences that begin like this:
- In nineteenth century England ...
- In The USA ....
- At the beginning of the second world war ...
When we have a sentence like A cafe is on the corner this sentence is difficult for the listener to process. Why? Well the part a cafe is new information here. We know this is the first time we talked about the cafe because we said a cafe and not the cafe. Because of this we are more likely to use an existential construction. We are more likely to use a sentence with There is or There were. The word there doesn't mean anything, so there is no new information at the beginning of the sentence. I instead the cafe and corner both come at the end of the sentence where they are easy to understand, easy to process.
Notice that if we talked about the cafe before, then the Original Poster's example is better:
- The cafe's on the corner.
This sounds much better because we know which cafe we are talking about. We are not introducing something new at the beginning of the sentence.
So if we want to say a cafe is on the corner how can we say it to make it easier to listen to, easier to process? There are two options. We can use an existential construction:
- There's a cafe on the corner.
Or we can use SUBJECT COMPLEMENT INVERSION. This is when we put the Complement of the verb BE at the beginning of the sentence and we put the Subject of the sentence after the verb. Usually when we do this, the Complement gives us information about locations or times. Look at the sentence:
Here the subject is of the verb BE is a cafe, the Locative Complement ( - the complement which tells us about the location of the cafe) is on the corner. If we use Subject Compelement inversion then we get this sentence:
This sentence is also good.
The Original Poster's Question
A cafe is on the corner is not a good sentence in English, although it is perfectly grammatical. The reason is that it puts new information that we haven't talked about yet at the beginning of the sentence. We can make the sentence better by putting the locative complement at the beginning. (Locative Complements are easy for listeners to understand.) Alternatively we can use an existential construction:
- On the corner is a cafe.
- There is a cafe on the corner.
Notice that usually when we use an existential construction, the noun that we are interested in is new information. Existential sentences with noun phrases beginning with the are quite rare. This is because we like to use the existential construction to make new information easy to process.
Hope this is helpful!