Here's an example :
"My tastes are very singular, you wouldn't understand"
Now my question is keeping this sentence in my mind we can substitue "wouldn't" with "won't" here right? But what would that mean here?
The simple answer: Yes they are, in this case, interchangeable
The accurate answer:
If we look upon the sentence from a theoretical viewpoint, the two sentences have slightly different connotations.
"Would" is the past tense of will (aux.v.). It is used as a conditionals and to express that something is unlikely to happen. (It is also used in polite requests, but in that case it is, as I explained here, a conditional).
"Will not" implies that there is as reason which hinders him/her from understanding your taste regardless of anything else. E.g.: "I will not tell you why therefor you wont understand it."
But only a pedant would correct you or be disturbed by your usage of "won't"
It is also worth noting that Google Ngram has around as many hits for "you would not" as for "you will not"
Try seeing the two versions this way:
"[I'll tell you about it but] you won't understand. (simple future negative)
[I'm not going to tell you because] you wouldn't understand (conditional future negative: i.e., wouldn't understand EVEN IF I were to tell you)
There is a tendency of using contracted form, for example -
I will -> I'll
We are -> We're
The contracted form won't results from woll not = will not
There are many variations of won't - for example, wonnot, woonnot, wo'nt - but they now are either obsolete or restricted in some dialects. Some of these variants are recorded as early as the 15C
won't emerged in 17C as the standard form.
The short form of will not is won't
Note - wont and won't are not the same, they are different. Contraction of would not is wouldn't.
As for the replacement in your sentence, yes, you can do that without any changes being made in meaning. But there is a slight difference in tone. By using would not you make the sentence less direct.