“Great meals are a dime a dozen in Bangkok.”
“Beautiful women are a dime a dozen in Seoul.”
“A dime a dozen” is a common phrase that means something is either very cheap or very plentiful. “A dime” is a ten cent coin, worth one-tenth of a dollar. “A dozen” means twelve.
Expanded it would be “ (it costs) a dime (to buy) a dozen (of those things)”
So the literal meaning is to buy 12 of something for 10 cents.
Traditionally some foods, like eggs and donuts, were sold in 12-packs. So a long time ago you would see sales that advertised cheap prices, like buying a dozen eggs for a dime.
We use it for things that are cheap, plentiful, or easy to get.
“Great meals are a dime a dozen in Bangkok.” = Great meals are very cheap in Bangkok. Not literally ten cents, but inexpensive enough to not cause a burden.
“Beautiful women are a dime a dozen in Seoul.” = There are so many beautiful women that the value of being a beautiful woman isn’t high.