Pros: simple development and deployment, easy local testing/debugging, and strong consistency with straightforward transactions. Cons: harder to scale parts independently, slower deploy cycles, and a growing codebase can become tightly coupled and harder to change safely.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "pros-and-cons-of-monoliths?"
function explain() {
// Start from the core idea:
// Pros: simpler development and deployment, easy local testing, straightforward transactions
}