"I have many pairs of shoes."
Translation:Tengo muchos pares de zapatos.
Why is it 'pares de zapatos'? (Similar structure to English).
Why not 'zapatos de pares'?
"Botas" means "boots" which even though it's a type of shoe doesn't translate to mean all shoes. This sentence means they have lots of shoes in general which could be a mix of boots (las botas), sneakers (los tenis), sandals (las sandalias), high-heels (los tacones altos), rainboots (las botas de lluvia), slippers (las pantuflas) etc, all of these are shoes but not the generic term for shoes.
Now here is where I get of my depth but IMHO this sentence is emphasizing the QUANTITY of shoes. If you said "... tipos de zapatos" you're emphasizing the VARIETY of the types shoes and not the quantity.
So if you said "...pares de botas" you're not "wrong" in that sense that it is a valid sentence. But now you are emphasizing that you have a large quantity of boots in general. These boots may or not be many of the same type, but the number of pairs is what's important.
In most translations "Pareja" means a pair of people like the way people say "We are a couple," = "Somos una pareja", It can also translate to partner, date, mate etc. But I believe the best translation of its use is a romantic couple.