Who can explain what it is?

Question

macOS

Actually every time I install something from MacPorts or Brew this pops up:
This formula is keg-only, which means it was not symlinked into /usr/local.
OS X provides an older sqlite3.
Generally there are no consequences of this for you. If you build your
own software and it requires this formula, you'll need to add to your
build variables:
LDFLAGS: -L/usr/local/opt/sqlite/lib
CPPFLAGS: -I/usr/local/opt/sqlite/ include
---
Actually a question - how to understand it? No matter how much I read on the Internet, I still don’t understand ..

Answer 1

This means that the version of sqlite3 that comes with OS X is outdated, so a fresh one was installed, and therefore it is recommended to manually specify the headers and linked libraries from the latest version (the same flags) when building applications.